Something like this needs to be incorporated by devs at the UX onboarding level if you want success.
During mass migration times, you need to really hold new users hands to curate a path towards community ideals. Needs to be as easy as clicking boxes to attempt to create accounts on multiple instances and then app defaults to the local option to start, or something similar.
You'll only get a few crumbs here and there from dedicated people if it's that manual of a process.