[jackson1442]

> It's up to the server whether it uses it in challenge-response or not. That's application-specific behaviour that's past the definition of passkeys themselves.

Do you have a source for this? After reading the W3 spec[0] this seems entirely antithetical to the Passkey model and additionally raises concerns about the integrity of hardware mfa devices.

[0]: https://w3c.github.io/webauthn/