This is unfortunately only possible if you still own the original domain. Think about it this way: if you could migrate domains without proving you own the original, then what’s stopping a bad actor from migrating any domain they want?

I'm suggesting a whitelist, that each peer has to put in a substitute list of vlemmy.ml==vlemmy.ml to re-federate.

Much like Reddit, comments continue to exist even when the author deletes their account.

That is NOT how the testing code of lemmy_server tests things, nor how the GitHub front page advertises Lemmy.