Google now lets you use your Android phone as a 2SV security key
If you have a phone running Android 7.0 Nougat or higher, you can now use it as a FIDO security key. This new option was announced at Google Cloud Next 2019, and it makes using 2-Step Verification much more accessible thanks to the fact that people are likely to have their phones with them most of the time.
The system -- currently in beta -- can be used to access ChromeOS, macOS or Windows 10 computers running Chrome, and can replace or supplement other FIDO-based security keys like Google's own Titan Security Key.