Use this advice at your own risk. This works best on side glass, not the windshield. It worked for me on some light scratches on a door window after a paintless dent removal guy (who is out of business now) carelessly let his tools dig into the glass while removing a door ding.
Dip 0000 steel wool in some scratch remover, and polish the area of the scratch. You'll soon be able to determine if this will help make the scratch less visible, or if the scratch is too deep to deal with. After you've gotten it out as much as you can, polish the glass with scratch remover and then a less agressive polish.
Note - I also tried this on the windshield of a car I did some restoration work on, to try to minimize a curved scratch caused by a bad wiper blade.
It didn't work as well, and with direct sun hitting the windshield, you can see light micro scratches where I used the steel wool. You wouldn't have this problem on side glass, which is more vertical, and that you aren't staring through while you're driving.