They do, it's called GHES.
https://docs.github.com/en/[email protected]/admin/over...
"GitHub Enterprise Server is a self-hosted version of the GitHub platform"
you're not getting copilot on the self-hosted version, which is what the parent was focusing on.
That does not include the Copilot related APIs though.
I've tried getting this set up at my University, it was hell dealing with them. We ended up going with Gitlab.