diff --git a/CHANGELOG.md b/CHANGELOG.md
index d3c27171f6..1bceb59b3f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Features
+
+- Expose `ITransport` and `SentryOptions.Transport` public, to support using custom transports ([#1602](https://github.com/getsentry/sentry-dotnet/pull/1602))
+
 ### Fixes
 
 - Workaround `System.Text.Json` issue with Unity IL2CPP. ([#1583](https://github.com/getsentry/sentry-dotnet/pull/1583))
diff --git a/src/Sentry/Extensibility/ITransport.cs b/src/Sentry/Extensibility/ITransport.cs
index 8725b9d437..7a2e6d6450 100644
--- a/src/Sentry/Extensibility/ITransport.cs
+++ b/src/Sentry/Extensibility/ITransport.cs
@@ -7,7 +7,7 @@ namespace Sentry.Extensibility
     /// <summary>
     /// An abstraction to the transport of the event.
     /// </summary>
-    internal interface ITransport
+    public interface ITransport
     {
         /// <summary>
         /// Sends the <see cref="Envelope" /> to Sentry asynchronously.
@@ -16,9 +16,4 @@ internal interface ITransport
         /// <param name="cancellationToken">The cancellation token.</param>
         Task SendEnvelopeAsync(Envelope envelope, CancellationToken cancellationToken = default);
     }
-
-    internal interface IFlushableTransport : ITransport
-    {
-        Task FlushAsync(CancellationToken cancellationToken = default);
-    }
 }
diff --git a/src/Sentry/Internal/Http/CachingTransport.cs b/src/Sentry/Internal/Http/CachingTransport.cs
index d651389291..bf9d4a6b9e 100644
--- a/src/Sentry/Internal/Http/CachingTransport.cs
+++ b/src/Sentry/Internal/Http/CachingTransport.cs
@@ -11,7 +11,7 @@
 
 namespace Sentry.Internal.Http
 {
-    internal class CachingTransport : IFlushableTransport, IAsyncDisposable, IDisposable
+    internal class CachingTransport : ITransport, IAsyncDisposable, IDisposable
     {
         private const string EnvelopeFileExt = "envelope";
 
diff --git a/src/Sentry/Internal/SdkComposer.cs b/src/Sentry/Internal/SdkComposer.cs
index 2d21e42a14..1925f3db13 100644
--- a/src/Sentry/Internal/SdkComposer.cs
+++ b/src/Sentry/Internal/SdkComposer.cs
@@ -52,7 +52,7 @@ private HttpTransport CreateHttpTransport()
             return new HttpTransport(_options, httpClient);
         }
 
-        internal void BlockCacheFlush(IFlushableTransport transport)
+        internal void BlockCacheFlush(CachingTransport transport)
         {
             // If configured, flush existing cache
             if (_options.InitCacheFlushTimeout > TimeSpan.Zero)
diff --git a/src/Sentry/SentryOptions.cs b/src/Sentry/SentryOptions.cs
index 8ffd8b2049..fce4c9b005 100644
--- a/src/Sentry/SentryOptions.cs
+++ b/src/Sentry/SentryOptions.cs
@@ -8,6 +8,7 @@
 using Sentry.Http;
 using Sentry.Integrations;
 using Sentry.Internal;
+using Sentry.Internal.Http;
 using Sentry.Internal.ScopeStack;
 using static Sentry.Constants;
 using static Sentry.Internal.Constants;
@@ -49,9 +50,13 @@ public bool IsGlobalModeEnabled
 
         /// <summary>
         /// This holds a reference to the current transport, when one is active.
-        /// If set manually (for tests), it will be used instead of the default transport.
+        /// If set manually before initialization, the provided transport will be used instead of the default transport.
         /// </summary>
-        internal ITransport? Transport { get; set; }
+        /// <remarks>
+        /// If <seealso cref="CacheDirectoryPath"/> is set, any transport set here will be wrapped in a
+        /// <seealso cref="CachingTransport"/> and used as its inner transport.
+        /// </remarks>
+        public ITransport? Transport { get; set; }
 
         internal ISentryStackTraceFactory? SentryStackTraceFactory { get; set; }
 
diff --git a/test/Sentry.DiagnosticSource.Tests/ApiApprovalTests.Run.Core3_1.verified.txt b/test/Sentry.DiagnosticSource.Tests/ApiApprovalTests.Run.Core3_1.verified.txt
index 93b767227c..c693bdc58d 100644
--- a/test/Sentry.DiagnosticSource.Tests/ApiApprovalTests.Run.Core3_1.verified.txt
+++ b/test/Sentry.DiagnosticSource.Tests/ApiApprovalTests.Run.Core3_1.verified.txt
@@ -498,6 +498,7 @@ namespace Sentry
         public Sentry.StackTraceMode StackTraceMode { get; set; }
         public double TracesSampleRate { get; set; }
         public System.Func<Sentry.TransactionSamplingContext, double?>? TracesSampler { get; set; }
+        public Sentry.Extensibility.ITransport? Transport { get; set; }
         public bool UseAsyncFileIO { get; set; }
     }
     public static class SentryOptionsExtensions
@@ -1038,6 +1039,10 @@ namespace Sentry.Extensibility
     {
         Sentry.SentryStackTrace? Create(System.Exception? exception = null);
     }
+    public interface ITransport
+    {
+        System.Threading.Tasks.Task SendEnvelopeAsync(Sentry.Protocol.Envelopes.Envelope envelope, System.Threading.CancellationToken cancellationToken = default);
+    }
     public class RequestBodyExtractionDispatcher : Sentry.Extensibility.IRequestPayloadExtractor
     {
         public RequestBodyExtractionDispatcher(System.Collections.Generic.IEnumerable<Sentry.Extensibility.IRequestPayloadExtractor> extractors, Sentry.SentryOptions options, System.Func<Sentry.Extensibility.RequestSize> sizeSwitch) { }
diff --git a/test/Sentry.DiagnosticSource.Tests/ApiApprovalTests.Run.DotNet5_0.verified.txt b/test/Sentry.DiagnosticSource.Tests/ApiApprovalTests.Run.DotNet5_0.verified.txt
index 76bfd2921e..76f8a81848 100644
--- a/test/Sentry.DiagnosticSource.Tests/ApiApprovalTests.Run.DotNet5_0.verified.txt
+++ b/test/Sentry.DiagnosticSource.Tests/ApiApprovalTests.Run.DotNet5_0.verified.txt
@@ -498,6 +498,7 @@ namespace Sentry
         public Sentry.StackTraceMode StackTraceMode { get; set; }
         public double TracesSampleRate { get; set; }
         public System.Func<Sentry.TransactionSamplingContext, double?>? TracesSampler { get; set; }
+        public Sentry.Extensibility.ITransport? Transport { get; set; }
         public bool UseAsyncFileIO { get; set; }
     }
     public static class SentryOptionsExtensions
@@ -1038,6 +1039,10 @@ namespace Sentry.Extensibility
     {
         Sentry.SentryStackTrace? Create(System.Exception? exception = null);
     }
+    public interface ITransport
+    {
+        System.Threading.Tasks.Task SendEnvelopeAsync(Sentry.Protocol.Envelopes.Envelope envelope, System.Threading.CancellationToken cancellationToken = default);
+    }
     public class RequestBodyExtractionDispatcher : Sentry.Extensibility.IRequestPayloadExtractor
     {
         public RequestBodyExtractionDispatcher(System.Collections.Generic.IEnumerable<Sentry.Extensibility.IRequestPayloadExtractor> extractors, Sentry.SentryOptions options, System.Func<Sentry.Extensibility.RequestSize> sizeSwitch) { }
diff --git a/test/Sentry.DiagnosticSource.Tests/ApiApprovalTests.Run.DotNet6_0.verified.txt b/test/Sentry.DiagnosticSource.Tests/ApiApprovalTests.Run.DotNet6_0.verified.txt
index 1bb34f5450..d314d070a8 100644
--- a/test/Sentry.DiagnosticSource.Tests/ApiApprovalTests.Run.DotNet6_0.verified.txt
+++ b/test/Sentry.DiagnosticSource.Tests/ApiApprovalTests.Run.DotNet6_0.verified.txt
@@ -498,6 +498,7 @@ namespace Sentry
         public Sentry.StackTraceMode StackTraceMode { get; set; }
         public double TracesSampleRate { get; set; }
         public System.Func<Sentry.TransactionSamplingContext, double?>? TracesSampler { get; set; }
+        public Sentry.Extensibility.ITransport? Transport { get; set; }
         public bool UseAsyncFileIO { get; set; }
     }
     public static class SentryOptionsExtensions
@@ -1038,6 +1039,10 @@ namespace Sentry.Extensibility
     {
         Sentry.SentryStackTrace? Create(System.Exception? exception = null);
     }
+    public interface ITransport
+    {
+        System.Threading.Tasks.Task SendEnvelopeAsync(Sentry.Protocol.Envelopes.Envelope envelope, System.Threading.CancellationToken cancellationToken = default);
+    }
     public class RequestBodyExtractionDispatcher : Sentry.Extensibility.IRequestPayloadExtractor
     {
         public RequestBodyExtractionDispatcher(System.Collections.Generic.IEnumerable<Sentry.Extensibility.IRequestPayloadExtractor> extractors, Sentry.SentryOptions options, System.Func<Sentry.Extensibility.RequestSize> sizeSwitch) { }
diff --git a/test/Sentry.Tests/ApiApprovalTests.Run.Core2_1.verified.txt b/test/Sentry.Tests/ApiApprovalTests.Run.Core2_1.verified.txt
index abe61dffc8..011d1d62f5 100644
--- a/test/Sentry.Tests/ApiApprovalTests.Run.Core2_1.verified.txt
+++ b/test/Sentry.Tests/ApiApprovalTests.Run.Core2_1.verified.txt
@@ -498,6 +498,7 @@ namespace Sentry
         public Sentry.StackTraceMode StackTraceMode { get; set; }
         public double TracesSampleRate { get; set; }
         public System.Func<Sentry.TransactionSamplingContext, double?>? TracesSampler { get; set; }
+        public Sentry.Extensibility.ITransport? Transport { get; set; }
         public bool UseAsyncFileIO { get; set; }
     }
     public static class SentryOptionsExtensions
@@ -1037,6 +1038,10 @@ namespace Sentry.Extensibility
     {
         Sentry.SentryStackTrace? Create(System.Exception? exception = null);
     }
+    public interface ITransport
+    {
+        System.Threading.Tasks.Task SendEnvelopeAsync(Sentry.Protocol.Envelopes.Envelope envelope, System.Threading.CancellationToken cancellationToken = default);
+    }
     public class RequestBodyExtractionDispatcher : Sentry.Extensibility.IRequestPayloadExtractor
     {
         public RequestBodyExtractionDispatcher(System.Collections.Generic.IEnumerable<Sentry.Extensibility.IRequestPayloadExtractor> extractors, Sentry.SentryOptions options, System.Func<Sentry.Extensibility.RequestSize> sizeSwitch) { }
diff --git a/test/Sentry.Tests/ApiApprovalTests.Run.Core3_0.verified.txt b/test/Sentry.Tests/ApiApprovalTests.Run.Core3_0.verified.txt
index 5136f07aa9..356fe74e29 100644
--- a/test/Sentry.Tests/ApiApprovalTests.Run.Core3_0.verified.txt
+++ b/test/Sentry.Tests/ApiApprovalTests.Run.Core3_0.verified.txt
@@ -498,6 +498,7 @@ namespace Sentry
         public Sentry.StackTraceMode StackTraceMode { get; set; }
         public double TracesSampleRate { get; set; }
         public System.Func<Sentry.TransactionSamplingContext, double?>? TracesSampler { get; set; }
+        public Sentry.Extensibility.ITransport? Transport { get; set; }
         public bool UseAsyncFileIO { get; set; }
     }
     public static class SentryOptionsExtensions
@@ -1037,6 +1038,10 @@ namespace Sentry.Extensibility
     {
         Sentry.SentryStackTrace? Create(System.Exception? exception = null);
     }
+    public interface ITransport
+    {
+        System.Threading.Tasks.Task SendEnvelopeAsync(Sentry.Protocol.Envelopes.Envelope envelope, System.Threading.CancellationToken cancellationToken = default);
+    }
     public class RequestBodyExtractionDispatcher : Sentry.Extensibility.IRequestPayloadExtractor
     {
         public RequestBodyExtractionDispatcher(System.Collections.Generic.IEnumerable<Sentry.Extensibility.IRequestPayloadExtractor> extractors, Sentry.SentryOptions options, System.Func<Sentry.Extensibility.RequestSize> sizeSwitch) { }
diff --git a/test/Sentry.Tests/ApiApprovalTests.Run.Core3_1.verified.txt b/test/Sentry.Tests/ApiApprovalTests.Run.Core3_1.verified.txt
index 93b767227c..c693bdc58d 100644
--- a/test/Sentry.Tests/ApiApprovalTests.Run.Core3_1.verified.txt
+++ b/test/Sentry.Tests/ApiApprovalTests.Run.Core3_1.verified.txt
@@ -498,6 +498,7 @@ namespace Sentry
         public Sentry.StackTraceMode StackTraceMode { get; set; }
         public double TracesSampleRate { get; set; }
         public System.Func<Sentry.TransactionSamplingContext, double?>? TracesSampler { get; set; }
+        public Sentry.Extensibility.ITransport? Transport { get; set; }
         public bool UseAsyncFileIO { get; set; }
     }
     public static class SentryOptionsExtensions
@@ -1038,6 +1039,10 @@ namespace Sentry.Extensibility
     {
         Sentry.SentryStackTrace? Create(System.Exception? exception = null);
     }
+    public interface ITransport
+    {
+        System.Threading.Tasks.Task SendEnvelopeAsync(Sentry.Protocol.Envelopes.Envelope envelope, System.Threading.CancellationToken cancellationToken = default);
+    }
     public class RequestBodyExtractionDispatcher : Sentry.Extensibility.IRequestPayloadExtractor
     {
         public RequestBodyExtractionDispatcher(System.Collections.Generic.IEnumerable<Sentry.Extensibility.IRequestPayloadExtractor> extractors, Sentry.SentryOptions options, System.Func<Sentry.Extensibility.RequestSize> sizeSwitch) { }
diff --git a/test/Sentry.Tests/ApiApprovalTests.Run.DotNet4_6.verified.txt b/test/Sentry.Tests/ApiApprovalTests.Run.DotNet4_6.verified.txt
index 5bb1bc77f1..b2119e26b2 100644
--- a/test/Sentry.Tests/ApiApprovalTests.Run.DotNet4_6.verified.txt
+++ b/test/Sentry.Tests/ApiApprovalTests.Run.DotNet4_6.verified.txt
@@ -497,6 +497,7 @@ namespace Sentry
         public Sentry.StackTraceMode StackTraceMode { get; set; }
         public double TracesSampleRate { get; set; }
         public System.Func<Sentry.TransactionSamplingContext, double?>? TracesSampler { get; set; }
+        public Sentry.Extensibility.ITransport? Transport { get; set; }
         public bool UseAsyncFileIO { get; set; }
     }
     public static class SentryOptionsExtensions
@@ -1037,6 +1038,10 @@ namespace Sentry.Extensibility
     {
         Sentry.SentryStackTrace? Create(System.Exception? exception = null);
     }
+    public interface ITransport
+    {
+        System.Threading.Tasks.Task SendEnvelopeAsync(Sentry.Protocol.Envelopes.Envelope envelope, System.Threading.CancellationToken cancellationToken = default);
+    }
     public class RequestBodyExtractionDispatcher : Sentry.Extensibility.IRequestPayloadExtractor
     {
         public RequestBodyExtractionDispatcher(System.Collections.Generic.IEnumerable<Sentry.Extensibility.IRequestPayloadExtractor> extractors, Sentry.SentryOptions options, System.Func<Sentry.Extensibility.RequestSize> sizeSwitch) { }
diff --git a/test/Sentry.Tests/ApiApprovalTests.Run.DotNet5_0.verified.txt b/test/Sentry.Tests/ApiApprovalTests.Run.DotNet5_0.verified.txt
index 76bfd2921e..76f8a81848 100644
--- a/test/Sentry.Tests/ApiApprovalTests.Run.DotNet5_0.verified.txt
+++ b/test/Sentry.Tests/ApiApprovalTests.Run.DotNet5_0.verified.txt
@@ -498,6 +498,7 @@ namespace Sentry
         public Sentry.StackTraceMode StackTraceMode { get; set; }
         public double TracesSampleRate { get; set; }
         public System.Func<Sentry.TransactionSamplingContext, double?>? TracesSampler { get; set; }
+        public Sentry.Extensibility.ITransport? Transport { get; set; }
         public bool UseAsyncFileIO { get; set; }
     }
     public static class SentryOptionsExtensions
@@ -1038,6 +1039,10 @@ namespace Sentry.Extensibility
     {
         Sentry.SentryStackTrace? Create(System.Exception? exception = null);
     }
+    public interface ITransport
+    {
+        System.Threading.Tasks.Task SendEnvelopeAsync(Sentry.Protocol.Envelopes.Envelope envelope, System.Threading.CancellationToken cancellationToken = default);
+    }
     public class RequestBodyExtractionDispatcher : Sentry.Extensibility.IRequestPayloadExtractor
     {
         public RequestBodyExtractionDispatcher(System.Collections.Generic.IEnumerable<Sentry.Extensibility.IRequestPayloadExtractor> extractors, Sentry.SentryOptions options, System.Func<Sentry.Extensibility.RequestSize> sizeSwitch) { }
diff --git a/test/Sentry.Tests/ApiApprovalTests.Run.DotNet6_0.verified.txt b/test/Sentry.Tests/ApiApprovalTests.Run.DotNet6_0.verified.txt
index 1bb34f5450..d314d070a8 100644
--- a/test/Sentry.Tests/ApiApprovalTests.Run.DotNet6_0.verified.txt
+++ b/test/Sentry.Tests/ApiApprovalTests.Run.DotNet6_0.verified.txt
@@ -498,6 +498,7 @@ namespace Sentry
         public Sentry.StackTraceMode StackTraceMode { get; set; }
         public double TracesSampleRate { get; set; }
         public System.Func<Sentry.TransactionSamplingContext, double?>? TracesSampler { get; set; }
+        public Sentry.Extensibility.ITransport? Transport { get; set; }
         public bool UseAsyncFileIO { get; set; }
     }
     public static class SentryOptionsExtensions
@@ -1038,6 +1039,10 @@ namespace Sentry.Extensibility
     {
         Sentry.SentryStackTrace? Create(System.Exception? exception = null);
     }
+    public interface ITransport
+    {
+        System.Threading.Tasks.Task SendEnvelopeAsync(Sentry.Protocol.Envelopes.Envelope envelope, System.Threading.CancellationToken cancellationToken = default);
+    }
     public class RequestBodyExtractionDispatcher : Sentry.Extensibility.IRequestPayloadExtractor
     {
         public RequestBodyExtractionDispatcher(System.Collections.Generic.IEnumerable<Sentry.Extensibility.IRequestPayloadExtractor> extractors, Sentry.SentryOptions options, System.Func<Sentry.Extensibility.RequestSize> sizeSwitch) { }