It wouldn't surprise me if no-one made such a mount. They wouldn't want to be liable for the damage it could cause to your head in an impact, either directly or by weakening the helmet. It would also be more work to fit and far less universal, limiting sales.
The least bad way of doing this would be to drill the helmet, and screw outwards into the mount, choosing screws with the flattest heads possible. Then at least you wouldn't have spikes on the inside. But drilling the helmet would only be strong enough for the camera with a hard shell, like a whitewater helmet or a minority of bike helmets. You'd end up cutting away at the foam for the screws to have somewhere to go. So by this point you'd have weakened the shell and the energy-absorbing foam - not a good start.
A design using clamp screws through existing vents would be no good either - unless designed for a very limited range of helmets it wouldn't fit, and would likely put hard bits where you don't want them.
I have a helmet camera for kayaking (cylindrical and side mounted rather than on top like a GoPro). That's held on with a strap, stabilised by thin thread. If I hit my head it will come off without much force, rather than yanking my head round. But there's also a light lanyard attaching it to the helmet strap using a plastic link that I can spring open with 2 fingers (it's carabiner-style keyring , so I wouldn't lose it, unless it snagged and I floated away - better that than it holding me in a strainer. I've used similar breakaway approaches for head-mounted lights on the bike - the thinnest cable ties, which snap if I don't duck enough for a low doorway.
Even the glued mounts carry some risk - they're actually really strong, and a knock in the wrong direction can drive the edge of the mount through a helmet shell.