But Git hosting isn't. As in the server/infra.

What is git "infra" to you?

An internet accessible reliable service that is always available for the public (others).

not really, it’s very inconvenient to use git without a centralized server

You can pull and push to pretty much anywhere, including directly to another person or workstation, over SSH. It's admittedly harder to have a single source of truth by doing so but it is still very possible to use in a decentralised fashion if you needed to.

Yes, this is a pretty common problem with decentralized services and I'm not sure we can fault git for at least making it viable.