We're self-hosting Gitea and run CI with Drone.
My main concern was exactly Copilot. The concern is mostly principal.
I don't hate Microsoft like I did when I was younger. I think VSCode is a great editor. I still think GitHub is the best social network I know. But I've quit every other social network.
But when your values don't align with an organisation's, you will eventually run into conflicts of interest.
I still push changes to open-source projects that I host on GitHub, but I don't create new ones. The latest project I started runs in a local git directory that will get pushed to a self-hosted Gitea.
When necessary, I'm seriously considering contributing to Gitea to make this transition easier for others.
Gitea is an ~100MB self-hosted binary that mimics GitHub, runs its own SSH server, and it looks GREAT!