There's also macholib (which is used by py2app for rewriting mach-o headers). 

Note that resigning for arm64 is possible using the following command:

$ codesign -s - --preserve-metadata=identifier,entitlements,flags,runtime -f <path to mach-O>.

This was mentioned in the Xcode 12 release notes.

BTW. My hobby horse w.r.t. a relocatable Python installation is to turn the current framework inside out: have a "Python.app" or "Python 3.10.app" that contains the framework and presents a GUI when double clicked (probably IDLE with some additional menu items). This would simplify the installation experience (no installer, just drop Python.app somewhere convenient).   

I have no idea if I'll ever get around to implementing this.