@jubei @cellularmoose @mastodonmigration @pluralistic
I don't know that this very long and technical thread addresses the interoperability question, but it definitely talks about At vs activitypub.
Perhaps more importantly, it talks at length about the degree to which Bsky is not distributed and as likely as not never will be. Not because it's not technically feasible, but because implementing the full stack costs way too much money.