If I’m logged in on one device, it would be nice to use that to login on another device, similar to what apps like What’s App and Discord have done.
A primary use case for facilitating 2FA to be more practical across a variety of devices. There’s really no great hardware option that works everywhere unless you’ve managed to get a USB-C exclusive ecosystem. NFC doesn’t work on the iPad or MBP, there’s no YubiKey A/C (you’d need to carry around your own adapter), there’s no A/lightning version either.
Supporting QR code would mean you could use NFC on the iPhone to login your desktop or tablet even if they don’t have NFC or any other option.
This would facilitate enabling 2FA using only a hardware token since compatibility substantially improves by proxy.
Right now in my case, I can’t rely solely on a FIDO since I don’t want to carry around 2 USB tokens for all my devices. a QR code solution would reduce that to one and allow for FIDO to be the exclusive 2FA method.