My understanding is the QR code is used to establish a quick BLE connection. The phone then pretends to to be a simple FIDO2 key. After that things proceed like any other FIDO2 workflow.
interesting, but it still needs an iPhone> -- I was kind of burned hard when trying to migrate my iCloud keychain passwords to something else so I'm curious how smooth it actually is
But there was a picture of them using it with a Windows machine. So they’ve thought of it.