> Sync is pull-based. Applications are responsible for staying in sync with all member PDSes. PDSes assist by sending lightweight write notifications to prompt pulls when new data is written.

It looks like this basically just reinvents ActivityPub (local servers can pull or push to remote servers). So it defeats all of the "benefits" you get from Bluesky's firehose-based approach anyway, except for the fact that Bluesky assumes you're going to be using their AppView and they will always have access to your private data.