You can do about the same thing with a single-user Mastodon instance right now.
It would be cool if you could do it with other server software: make a backup from your 1-user Masto, and restore it to your 1-user Calckey. Change the DNS, and it just works.
@kissane this is, obviously, how Blue Sky data portability works. Everyone gets a DNS name for their identity. And they move around as needed.