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
The problem articulated in the report is indeed an open problem for which there currently is no solution. Non profits such as numfocus or Software Freedom Conservancy are only part of the answer. Organizations such as the Linux Foundation are part of the problem. Unfortunately, to the Free Software developers and the general public, they all appear to work towards the same goal. This tension is unlikely to be resolved any time soon and we, individual software developers, are mostly on our own to figure out a sensible way to sustain the work we do.