Yes there are other options: gitlab.com, some project specific gitlab instances (freedesktop for example), forejo / codeberg, and the Linux kernel is off doing it's own thing with mailing lists instead. I even come across code on SourceForge every now and then still. But all of these are super niche.
I genuinely don't know, got curious and went to typescriptlang.org to find some "About" page or "Governance" or something else, but couldn't find anything at all about it. It was exclusively developed by Microsoft for two years, and with no other clear governance/decision structure today as far as I can see, doesn't that exactly mean that Microsoft controls the entire "organization"? It's not clear what "organization" you're referring to either, the GitHub organization? I'd assume that's also 100% Microsoft controlled.