I'd agree - technically speaking, there's no real barrier to a secure way to export from a FIDO key. HSMs have support for it - authenticate to the HSM, provide

I'd agree - technically speaking, there's no real barrier to a secure way to export from a FIDO key. HSMs have support for it - authenticate to the HSM, provide an encryption key (or public key), and receive an encrypted dump. I do fear resistance from the big tech "overlords", trying to protect non-technical end users from an "endgame" type phish attack, where their device is compromised and they unwittingly export a backup encrypted to an attacker-controlled key. From what I've seen so far (you may have a better idea than me), Apple and Google are giving "dip your toe into the swimming pool" type ways of sharing passkeys, but which actually revolve around scanning a QR code (proximity) shown on the (unpaired) screen/device using your (trusted) phone, which then uses BLE and similar short-range comms to let you sign in. I am not aware of any proper "migration" that takes you off one platform and onto the other platform - the above is fine as long as you never break your phone (or can afford to instantly replace it with one from the same ecosystem), but makes no provision for someone wanting to move from iOS to Android, or to get rid of their phone and move to an authenticator in their browser on Linux. In the real world, people smash and break phones, and drop them in the ocean - there need to be recovery modes from this. A good Webauthn key will likely outlast at least 2 generations of current shiny gadgets. Finally, all of this assumes users have unlimited resident key storage - most dedicated hardware keys are limited on this front, and I do hope we see options for people who want to stuck with UN + PW + FIDO2 (non-resident, as MFA). Even though I have confidence in the crypto, I like to separate concerns. A dedicated bit of hardware that can be unplugged from the USB port can resist attacks that on-platform TPM/secure elements can't, and is also inherently portable. And FIDO2/Webauthn today with non-resident keys is hugely portable (and even more portable if there was a way to pair friendly backup keys at time of initial registration).