> Git is decentralized, GitHub is just another place you can host your code in, but you can push your code to multiple remote servers.

That's precisely what I have been doing for years, I still get to keep one foot in the GitHub ecosystem. I still get most contributions on GitHub, and that's fine by me. When a PR comes it I check it out locally, review it, and when it's done I merge locally to master, push to origin, and then origin pushes to GitHub which then automatically closes the PR and gives the author attribution. I never actually have to interact with GitHub after the initial pull.