“a single proprietary solution Github by Microsoft”
Moving (Edit: Just the code, not issues and not pull request information) away from GitHub is trivial, since Git itself is open source and distributed, requiring merely setting up a repo on the new server (such as the open source Sourcehut) then running these commands:
git clone https://github.com/foo/bar
vi bar/.git/config # Add new remote location
cd bar
git push baz master
(Replace foo, bar, and baz with real names)