On waiting for the protocol to keep things private: Atproto Spaces is the answer and it is close. It gives access control rather than encryption, though: readable by whoever runs the space. That is a real improvement on world-readable, and it is not the same as private. The difference matters when you are deciding what to trust it with. So some of it will move once Spaces is stable, and some of it may never move. It is alpha today, and I am not promising a date. Full disclosure: I am building the thing, so treat my enthusiasm accordingly.