As I was finishing up my Drop in Audio blog post, Jam, an open source Clubhouse-like system debuted on ProductHunt. I took a quick look at the code and it requires a few moving pieces and Docker, but it's a great little starting point.
After a good discussion with @flancian, I added a section to the Git Siphon for Moa Party to focus on post-per-file. We discovered that we need to think about Moa Party as being standalone with multiple clients. Anagora is a client, people's individual gardens are clients, eg. my Jekyll site.
This may mean that making Moa Party become a whole Micropub server that publishes to Git may make sense. IndieKit has a whole template system so that people can run a variety of git-based static site generators with it.