This app requires macOS Big Sur, it provides a simple interface to mount APFS System snapshot as writeable on a temporary mount point, then during that phase can make any system modification directly from Finder (if close Finder to find the System rw mount point simply from Disk Utility or easier unzip the attached alias to desktop), keep running the app until you made the modifications (keep a backup of replaced item), when done simply click "Rebuild KC" button.
It is mainly for unsupported Big Sur Mac but should work also from a supported Mac, only requirements are:
- csrutil disable
- csrutil authenticated-root disable
- from a recent T2 Mac is required to boot CMD+R and disable security as explained here: https://support.apple.com/en-us/HT208198
Added also an updated version for multiple APFS macOS and BigSur installed sharing the same container:
https://github.com/jacklukem/BigSurmountsrw/releases/download/1.0/BigSurmountsrw2.app.zip