I was wondering why there’s nose pads; but looking closer I think there’s a pin sticking out of each lense that gets inserted into the implanted nose bridge making a hinge of sorts. (instead of a screw) The lenses are held firmly in two axis; but can rotate up/down to rest on the nose pads, while being removable.

I’d be worried about bumping/catching them on anything and ripping that piercing/implant out too, but I don’t think magnets would be strong enough to stop them moving around with any sort of g-forces.

As someone who sleeps face down quite a bit, I’d never try this. It would definitely drive me nuts just trying sleep with that bridge in, plus it would get snagged on bedding/clothes/towels/etc.