I had a different post that didn’t really answer your question. A real answer is that it might not be as much of a problem as you might imagine. Biometric verification is really insecure: something like a 1% false positive rate for fingerprints.

Ideally people would just use passwords like back in the olden days. Longer strings are more secure than random characters.

Edit: should clarify this was for fingerprints unlocking an iphone