...Maybe that's the answer, we need a "hub" for the smaller missing things to start, you pop in your git repository when you join, and it can sit as a thin layer over your repo with issues, releases, etc... Sounds like a lot of work, but doing it piecemeal would do it.

I think trying to re-host git itself might be more trouble than its worth. My kingdom for someone to build this so I don't have to use ADO boards anymore.

Like some kind of UI over a database scraped by code which understands Github, Forgejo, Gitlab, sr.ht, etc?

One issue is that issues tend to be monotonically increasing numbers, and references to old issues vs. new issues get confusing over time.