I think the other reply here might be missing something because while I have not read the whitepaper, the announcement touts these two benefits of deeper FIDO commitment:
> 1. Allow users to automatically access their FIDO sign-in credentials (referred to by some as a “passkey”) on many of their devices, even new ones, without having to re-enroll every account.
> 2. Enable users to use FIDO authentication on their mobile device to sign in to an app or website on a nearby device, regardless of the OS platform or browser they are running.
Point number 2 directly invokes cross-device, cross-platform authentication. It sounds like "you can use your iPhone or Android to sign into a website on your Windows PC" to me. Whether passkeys might actually sync between iCloud keychain and whatever Microsoft offers seems unclear but much less likely
> 1. Allow users to automatically access their FIDO sign-in credentials (referred to by some as a “passkey”) on many of their devices, even new ones, without having to re-enroll every account.
> 2. Enable users to use FIDO authentication on their mobile device to sign in to an app or website on a nearby device, regardless of the OS platform or browser they are running.
Point number 2 directly invokes cross-device, cross-platform authentication. It sounds like "you can use your iPhone or Android to sign into a website on your Windows PC" to me. Whether passkeys might actually sync between iCloud keychain and whatever Microsoft offers seems unclear but much less likely