Auto parts stores have headlight renewal kits. I just used one to polish the headlights on one of my daughter's car. Headlight lenses nowadays are plastic. Some are better quality than others. The kit I used has two grades of abrasive cloth, two grades of polish and a buffer and a protectant.

All the while I was working, I was wondering if the kit would work on model airplane canopies.

The problem with scratches compared to oxidation is that scratches can be a lot deeper. Back in the old days, there were some reports of guys rubbing out scratches with toothpaste. That suggests that scratches aren't always too deep. Unfortunately, today's toothpastes probably don't have abrasives in them anymore.

whatever......