Oh gawd. Clean install. You have no idea (you probably do) how much I'd have to install 'fresh'. It would be an entire day of just installs.
Thanks though, under consideration.
Had to do clean install with upgrade to Catalina Oct 2019. Yes, a day, yes it worked. Takes an hour or two to install, same with a new iPhone but still the customizing and getting working.
There's a lot of change that has happened with where and how the system is laid out. Migrating can introduce problems. Step #1 might be to use new Mac "as is" to insure everything works as it should. When troubleshooting and diagnosing - introduce one change at a time. Urban lore, wait 3-4 months for issues to surface in hardware/software, even production changes.
Ran across two sites with m1 Big Sur compatibility chart - native, Rosetta 2, version, the state of support.
There are issues with pre-11.1 with reinstalling, erasing, recovery, which is terrible, and with ability to create a second system volume - handy for testing a system. *Sometimes* just a new user account to see if a problem lies in user account, often in home ~/Library.