Sourcehut is something you might want to look at. It's modular, so you use what you use, and ignore the rest.
The CI they offer makes no assumptions about where your repos might live (git is git. Who cares who the host is), and offers the stuff you might need like secrets, ssh keys, etc. The images they supply for testing actually seem more extensive than the other players.
And if you really want to self-host it... Go ahead. The whole of sourcehut is open source and reasonably well documented. You can host your own build server with minimal fuss.
Interesting, I didn't know it would support pulling from other git hosts. It looks like their CI even has an API integration with GitHub at least for PRs. That's looking like a potential winner. Thanks for pointing that out.
The CI they offer makes no assumptions about where your repos might live (git is git. Who cares who the host is), and offers the stuff you might need like secrets, ssh keys, etc. The images they supply for testing actually seem more extensive than the other players.
And if you really want to self-host it... Go ahead. The whole of sourcehut is open source and reasonably well documented. You can host your own build server with minimal fuss.
[0] https://sourcehut.org/