I gave a short (15 min) talk at CSVConf last month about federated social media, trust, and how we can better define community boundaries. In particular, I discuss the importance of local-only content that never federates, and the ability to tag other servers as "trusted" and federate things only to those servers. That last idea is something I call "neighborhoods".
Non-youtube direct mp4 here: https://tinysubversions.com/talks/csv-conf-2019/video.mp4
Hometown is adapted from Mastodon, a decentralized social network with no ads, no corporate surveillance, and ethical design.