I've some light plastic panel lamps to fit. The centres (bases) are attached (3 "self tapping" type screws supplied), the lamps themselves twist onto the bases. On the back of the plasterboard is a film of Visqueen. I don't want to pierce the Visqueen, which is loose, just laid over the PB, so there's a little "give", but pointy things might not be a good thing.
Gripits don't pierce. It's a plasterboard thickness disc with two wings that rotate once inserted and lodge behind the plasterboard
I looked at them; a screw goes through (I guess I could cut some down). Might be able to do it with a "worm" one. Unsure.
You can get them with metric threads as well. You could cut your bolts to length and/or round the ends over
https://www.screwfix.com/p/fischer-plasterboard-plugs-hdf-10-x-28mm-100-pack/58219 these have worked pretty well in other applications, if you’re carful with your screw length end of the screw should be covered by the bit of plastic at the back edit: Maybe not with those self tapping screws, might be too big
For your application, I would just grind off the points, and use suitably sized / length self tappers. There's almost nothing weight wise to them light fittings.