Discord and Steam have a user login flow that is very similar to what SQRL was aiming for, including a QR code alongside the username/password fields. While it's a closed implementation of a different system, I think of SQRL every time I use it.
I might be biased, I used the PPP Pam module on linux for years, until I moved to TOTP, and then eventually to pubkey-only.
I might be biased, I used the PPP Pam module on linux for years, until I moved to TOTP, and then eventually to pubkey-only.