> Firefox doesn't even support this stuff properly yet

What OS are you referring to? It works perfectly on macOS now, and I believe Windows has been supported even longer.

> The same happened with OpenID. Both MS and Google were all over it. But they couldn't bring themselves to federate each other's identities.

I wouldn’t call this a comparable situation. Passkeys are very interoperable (save for sites doing incompetent browser sniffing, “sorry, Firefox does not support passkeys” etc.), but there is a factor of platform lock-in.

Not great, but much more feasible to address since any fix can be done purely on the implementation backend without changing the API.