yeah, what we’d really need is issuing ActivityPub Move events for community actors (afaik both Lemmy users and communities are actors on the ActivityPub side, thus communities can be followed / posted to from Mastodon, too). this would allow moving communities between servers to make sure that followers of the old community just carry on following the new community

I guess moving followers of users would behave in a similar way, albeit probably much less critical for the health of communities