Your favorite search engine or LLM will show you in a second, it's really easy.
The problem is that it's not enough. The fact that Github uses Git specifically is a technical detail; it could use mercurial equally easily, as Bitbucket used to. Github Actions, OWNERS files, PRs and review tools, issue tracker, wiki are all not Git features.
Not a chance. I think you need to spend some time in low ball corporate IT. It's just monkeys throwing faeces at the wall. We only just levered them off subversion...
(I use Fossil 100% offline for personal projects for ref)