Yeah, I attend the FedCM meetings. Firefox has one dev working on it who attends regularly. I have found some posts where the safari team has said "seems like a good idea, we'll consider implementing" but have not seen further action.

Edge supports it, and it should be relatively easy for the other Chromium based browsers.

- https://github.com/WebKit/standards-positions/issues/309

- https://github.com/mozilla/standards-positions/issues/618