[barkerja]

Passkey support has been on iOS since the release of iOS 16 -- so more than a half-year!

Google has actually had support for passkey for many many months now, but for whatever reason, waited to formally announce it until just recently.

Cross-platform is also already solved. See the FAQ directly from the FIDO Alliance: https://fidoalliance.org/passkeys/#faq

[howinteresting]

> If the user does not have their old device or a security key, then the RP can treat sign-in from the new device (which might be from a different vendor) as a normal account recovery situation and take appropriate steps to get the user signed in.

LOL. This is not a serious answer.