@Pete Glad the module is working for you!
Yeah, the bypass permission will be a useful addition. I agree that this permission should hide the input field completely. Not sure if I can prevent the input field wrapper markup from showing up altogether, I'll have to give that a try.
One thing I'm concerned about is that superusers won't see the hCaptcha input at all, so some site admins might think the module is broken if they add the inputfield to a form and don't see it in the frontend (unless they test in a private browser window). Maybe instead of hiding the inputfield, it should display a static message? Something like The captcha is hidden because you're already a verified user. Or is that too confusing for users?
Anyway, I'll try to build this in a feature branch this week for testing purposes!