A contractor showed me how to fix dents in granite with superglue. It’s totally clear. The trick is to scrape it with a razor blade at a 90 degree angle (strait horizontal). The imperfections become nearly invisible.

This is also how glass chip repair works. If the polymer has a close enough index of refraction to the glass, it's invisible.

I've been told this is a cheap way to fix small windshield cracks. Never tried it but sounds like it would work for the small spider sized and shaped cracks from small rock impacts.

This is basically what the glass repair kits sold at auto parts stores are. (They also include a suction cup with syringe, to vacuum any air bubbles out.)

And, bringing this topic full circle, the chemical in those kits is methyl methacrylate!

The expensive way is superglue plus a little suction cup to evacuate the air, and a razor blade.