Steven Troughton-Smith has spent some time testing one route to get from x86 to ARM for Mac apps:
Of course, the specter of macOS on ARM has been in the public psyche for many years now, and many have pondered whether Bitcode will make this transition more straightforward. The commonly held belief is that Bitcode is not suited to massive architectural changes like moving between Intel and ARM.
I was unconvinced, so I decided to test the theory!
I don’t think Apple would automatically recompile everything in the Mac App Store for ARM, but I do think this will be the way forward for Mac developers as the Intel Mac Era comes to a close very soon.