Even two years on, I still have no idea which direction #Bluesky is intending to go. Though it seems like if they wanted to adopt an existing protocol, they would've already done so.
I'll only say that the challenges of building a decentralized social network are anywhere but the actual protocol. Mastodon started on one protocol, then switched to another. Decisions that matter are in product design. Marketing.
If they propose a new protocol, what would make it worth resetting all that to zero?