Page-level password case insensitive?

I want to password-protect a page with a case-insensitive password for a client. This password is less about security and more about minimizing nosy folks who weren’t invited to the event. In any case, the client would like the password to work even if the guest doesn’t get the case correct.

I found the “Case-Insensitive Passwords” plugin which can make login passwords case-insensitive, but didn’t seem to work for my page-level password. It’s also six years old and didn’t seem to get much use, so I can’t imagine the author is super keen to update it.

So… Have I missed the plugin that exists to do this? And if not, where do page-level passwords get stored? The best answer I’ve gotten to this question is “in the database”. If someone can help me narrow that down, I’d appreciate it immensely!