Actually, what’s your specific concern with GitHub? That you may have a networking issue that makes GitHub inaccessible, or that GitHub itself could have robustness issues that seize your workflow?
FWIW, this is something companies worry about quite a bit.
Google opted not to use GitHub to coordinate Chrome and Android open source development because (among other reasons) they were concerned about GitHub’s single point-of-failure. At the time GitHub was only able to serve out of one datacenter. Instead Google developed a multi-master Git service and their own CR/CI system, Gerrit.
Presumably Microsoft also learned that they were becoming very strategically dependent on GitHub and solved this problem by acquiring them.
I believe GitHub has addressed the all-eggs-in-one-datacenter concern since then though.