I love this. It is close to what we've built with Peergos [0].
1. People have to accept you as a follower, and the default is bi-directional.
2. There are no visible follower/friend counts.
3. Chronological feed which has an end (no infinite scroll)
4. No arbitrary character limit
5. No analytics (enforced by E2EE)
We don't have a max friends/number of posts per day though.