I've seen discussions that Mastodon has a way of migrating accounts. I don't know if that's a Mastodon specific thing or at the ActivityPub level. I don't think

I've seen discussions that Mastodon has a way of migrating accounts. I don't know if that's a Mastodon specific thing or at the ActivityPub level. I don't think it migrates the content but I'm not sure. What I think it does is notify followers of the migration. I'm not sure anything like PKI is necessary. Conceptually a planned migrations should have a period of concurrent access to both the old and new accounts and it should be easy to publish a handshake to confirm the migration to followers to update contact info. That's my thought anyway. Something like keybase (does that still exist?) could also be used for similar sorts of proofs. The way people used to handle this on Reddit is people would send a message from their old account saying "hey XYZ is my new account" and that seems sufficient.