> I wish there was a stronger differentiation between syncable and device-bound passkeys.

But there is no difference. I'd prefer if services just let me generate a passkey and leave it entirely up to me how I manage it. Whoever setup granny's device should have done so with a cloud based manager.

I think Google tries to make some confused distinction, or maybe that has more to do with FIDO U2F vs FIDO2. There you can add either a "passkey" or a "security key", but iirc I added my passkey on my security key so... yeah