An answer to "Creating a passkey for your Apple account?" explains that iOS should automatically register a FIDO2 key with Passwords (per-device) for the Apple account.
Consequently, I want to authenticate via the "Sign in with passkey" button (//*[@id="swp"]) at account.apple.com/sign-in:
According to "Can I transfer passkeys generated inside Keychain outside Keychain?", exportation of 3rd-party credentials from Passwords is possible on at least iPhoneOS, via the Credential Exchange Protocol. However, this does not appear to include Apple’s:
Is this, perhaps, possible via macOS?
