Sec fetch has 98% browser coverage now. You can fall back to origin, which has 100% coverage.

Non-browser clients can be either blocked or even just given a pass, since CSRF is about tricking someone into clicking a link that then sends their Auth cookie along with the request. Either the non-browser request includes a valid cookie in the request and is allowed to mutate state, or it doesn't and nothing happens as the request doesn't get authenticated.