I’ve posted this link, and the other link as they describe “how OSS is built” from community management through to different types of projects, and while it isn’t directly related to federation, I think they are useful reads as it provides insight into various projects. I found reading Nadia’s book very insightful, and was able to directly relate various aspects to what is already being done in Gitea.
Edit: The other link I am referring to is Working in Public: The Making and Maintenance of Open Source Software