It doesn’t matter if other authenticators could work if a relying party refuses to allow its users to use them.
> Also, end users are already locked into Chrome and Safari …
Not this end user; I am typing this in Firefox right now. Not coincidentally, WebAuthn is yet another bit of complexity making it slightly more difficult to implement a browser. From the perspective of the big tech companies, end users aren’t expected to write software, or to run anything the big tech companies haven vetted.
You keep repeating that, but that's not possible anymore, since both Apple and Google removed attestation from their respective passkey/WebAuthN implementations.
For details, see >>42522490 .