Mozilla will be landing this change in Firefox soon: https://bugzilla.mozilla.org/show_bug.cgi?id=1956484. Chromium already supports this behavior, as I already noted in the original request. It would be great to get parity across the extension platforms and continue to promote passkeys as the preferred authentication mechanism over passwords.
Just to clarify the functionality being requested: Safari extensions should be able to create and use passkeys for domains that they are associated with or have host permissions for. So, for example, instead of only being able to use passkeys bound to a ephemeral Safari Extension origin (i. e. safari-web-extension://UUID), to use passkeys bound to the company's domain (i. e. example.com).
I've yet to hear back in Feedback Assistant. How can I better escalate this feature request?