I run their act binary on one of my servers. Can’t remember much of the setup, so I can’t be too bad. I did have to change the used images though, but I guess that comes with maintenance of you own runner anyway.

That was my first thought as well. 😁

I’m using gitea which has CI compatible to GitHub actions with my own runner. It’s pretty straightforward to set up and didn’t give me any headaches yet. It’s a very small instance just for my ownaybe dozen projects though.