You can clay and polish glass no problem. In fact these steps are taken before applying glass coatings. I'd look into glass coating but FWIW I've used Megs UQW/D156 and OCW on glass with no problems.
Just make sure you don't use it on the windshield. Wipers will remove it and in the process it will make looking out of the windshield difficult. I have had a very bad experience to learn that
I've used collinite 845, megs 21, hydro 2 and spray waxes all on the windshield. I've never had issues. I've used pinnacle coating or sealant and didn't let it dry long enough and it was a real pain to buff off. So i stick to wax or sealant