Wow, awesome! We've had a few startups ask for an HN integration at https://clerk.dev and we'll build this in ASAP.
It would be great if this could somehow verify whether an HN account has been part of YC cohort. A few requests we've received were with the hope of offering early access to YC founders-only before a public release.
Also, I love the OTP solution instead of asking for our HN passwords.