[ghancock]

This was on an iPad. My experience before had been that I was able to register an iCloud passkey for Google 2SV when using Safari on iOS/iPadOS, but I was unable with Chrome.

At that time, I inspected the registration request Google sent to Chrome and found it was passing a private option that Chrome recognized. According to what I found in web searches for it, the option created a legacy U2F key, and they needed to do that because there were existing Android devices that they could not upgrade and that would not support log-in with WebAuthn keys.