I tried Cerium Oxide which is regarded as able to remove scratches. HOWEVER, the rule of thumb (minor pun intended) is if you can run your fingernail over a scratch - and feel it, it probably isn't coming out.
I have a '64 Studebaker Daytona sedan that came with a cracked windshield. The last Studebaker was manufactured in 1966 and the likelihood that anyone is still making replacement windshields is nil. I searched for over two years looking for one. Eventually I had to settle for a convertible windshield that required cutting about 3/8" out of the corners. The windshield also had a bull's-eye and numerous scratches. It cost me $100 and was 400 miles from my home. Thankfully my son was in the area and delivered it to me.
Anyway, enough of my whining about vintage glass. I used the Cerium Oxide with a buffing wheel attached to a Dremel. Even after an hour working on a 2" long scratch it really didn't seem to make a difference. So, I'd say except for the finest of scratches I doubt you will get anything noticeable out. Also be aware that removing a scratch means removing glass. It is possible to create a depression that can distort your vision as well as leave a low spot the wiper can't clear.
BTW, given my issues with finding a Studebaker windshield, I invested $20 at a recent Pick Your Part 50% off sale to get a spare for the Pinto.
Tom