What are the mobile prospects here? Sound like the main motivation is that phone numbers are not secure second factors. But the result is a solution that only w

What are the mobile prospects here? Sound like the main motivation is that phone numbers are not secure second factors. But the result is a solution that only works on desktops (is that correct?) and requires a physical key that can be easily lost. Modern phones now have secure coprocessors and biometric authentication. Why not use that method for the second factor? It doesn’t rely on a phone number and it would handle both mobile and desktop.