feat: Initialize runtime exports at startup

src/Uno.UI/ts/ExportManager.ts

@@ -0,0 +1,16 @@
+// eslint-disable-next-line @typescript-eslint/no-namespace
+namespace Uno.UI {
+
+	export class ExportManager {
+
+		public static async initialize(): Promise<void> {
+
+			if ((<any>Module).getAssemblyExports !== undefined) {
+				const unoExports = await (<any>Module).getAssemblyExports("Uno");
+				const unoUIExports = await (<any>Module).getAssemblyExports("Uno.UI");
+
+				(<any>globalThis).DotnetExports = { Uno: unoExports, UnoUI: unoUIExports };
+			}
+		}
+	}
+}

src/Uno.UI/ts/WindowManager.ts

@@ -61,7 +61,7 @@ namespace Uno.UI {
 		private static buildReadyPromise(): Promise<boolean> {
 			return new Promise<boolean>(resolve => {
 				Promise.all(
-					[WindowManager.buildSplashScreen()]
+					[WindowManager.buildSplashScreen(), ExportManager.initialize()]
 				).then(() => resolve(true))
 			});
 		}