How will you be able to setup a new phone then? Let's say next year you buy a phone. Will you have to disable advanced protection on you account to add the phone to your account?
I enrolled a key this way (USB-A key plugged into an adaptor on the USB-C port) once just to see if it works. Bizarrely Google will let you do that, but, having proved that it works, they then immediately tell you that you need to install Desktop Chrome before you can enroll any other keys. No idea why they think that's a good idea let alone necessary.