Given Threads statement that THEY will support account migration out to Mastodon and other ActivtyPub networks would seem a critical thing to standardize fully in ways that we want for the good of the Fediverse platforms.
I did some inventory on which platforms now support migrating Mastodon accounts into, and supports exporting social graphs OUT to Mastodon and it seemed like this:
Mastodon (of course)
Calckey (including the ability to move posts)
Pleroma
Mitra
Do I have that list right? Would be good to include in any documentation we do which Fedi platforms support this defacto standard now, and the full standard in the future.