It’s funny you mention that — I just started such a project (three hosting modes: centralized, federated, fully decentralized) as an educational series to teach software development on multiple levels. It’s very early (read: non functional), and I’m still figuring out the best way to teach and build simultaneously, but constant weekly progress is being made.

Educational site (I’m backporting the previous sessions to the site, session 7 is the first one hosted right now): https://www.codewolfpack.com

Project repo: https://www.github.com/HowlerChat/Howler