Remember that critical industry is a sector where patching software is viewed as risky, because changing anything when it works is seen as unnecessary, and would often have weeks or months of pre-deployment testing. They work on a different time-base to the IT world.
The ability to do a "bypass" is nice in theory, but the need for this option will resonate with the "old guard", who will be able to use this external dependency to keep it out.
Personally I prefer smartcard-based solutions for MFA, since you can do all verification offline without requiring any third party to inject themselves into the chain. I found a good example of a vulnerability this year in Duo that just shows their validation logic is complex enough that one user was able to pass 2FA as another user [1].
That's probably your second worst case scenario, with the worst being an outsider being able to pass 2FA. A well-implemented smartcard scheme shouldn't fail in this way, as you're distributing validation logic to each device, rather than centralising it and relying on a "trusted outsider" to give a "yes or no".
[1] https://sensepost.com/blog/2021/duo-two-factor-authenticatio...