@kissane
Great post! I started here by deciding that I want to test the migration first, and dug up my circa-2018 accounts (two) to migrate both of them to this account. Doing that, I ran into all of the stuff you mentioned, too.

I also ran into the ludicrous take that basically not migrating toots is Just Fine(tm) and expected, because No One(tm) should have old toots anyway, because Ephemeral and everything is set to auto-delete.

I had to conclude these people have no friends or family.