Is Git decentralized?

Git is, but with GitHub being treated as the golden repo for projects, it becomes the hub of other parts of development, like PRs and CI/CD pipelines.

Yes. But in practice people need their `if any_tasks_failed: throw error` (“CI”) to be in the cloud and have three nines of uptime.

Personally (but who am I) I don’t need to check whether my changes work on Windows 7 and SunOS in order to continue on a project most of the time.