[Radicle](https://radicle.dev/) gets a wee bit closer. It’s selfhostable and federated. You’ll have a hard time finding something with the same social gravity well as GitHub; it remains to be seen whether that’s a separable element or if it needs to ship as part of the forge itself.

I think it's currently non-selfhostable. You can host your own git server (knot) and CI runner (spindle) but not really the UI/API itself, but they're working on changing it. Currently it's a bit centralised

I’d be interested too. Besides the fact that the company appears to be registered in Finland, I haven’t been able to find any information on who’s behind this, how they are funded, etc.