Comment by grishka

Your instance is in your username. The full username is "@grishka@mastodon.social". You use WebFinger (https://mastodon.social/.well-known/webfinger?resource=acct:...) to convert that to the ActivityPub actor ID, which in my case would be "https://mastodon.social/users/grishka".

And yes, that's one weakness of this system — there is no "real" account migration. Most you can do is set up two-way references between your old and new accounts and ask your followers to unfollow the old one and follow the new one. But your past content doesn't carry over.

But then idk, Bluesky's identity service is completely centralized, so the fediverse is better with regard to independence?