I suspect the OP just wants to rip off the touch screen digitiser and replace it with a glass variant (similar to some of the ones we see on phones, or perhaps around here those glass fronts that we saw the original GBA get a little while back), but also retain touchscreen functionality. I am guessing the harder to scratch nature of glass is more desired than the drop resistance of plastic.
As for the question no idea if people have gone there yet. However where I might expect someone to custom cut some glass sheets and bundle it with some UV curing resin or something then I doubt we will see anything with a custom touch panel for many years yet and thus the best option is likely to be a screen protector.