You could replace the screen if you want it new again. It’s a bit hard to do, but it’s doable. You can find places like iFixit (I did not look to see if iFixit actually has any) that will sell you a new screen, or you can purchase an old used watch for ~$30 (depending on your model) and transfer the screen from the used one to yours.
Having said all that, they do sell stuff to minimize the scratches. Typically it comes in a tube. Not very expensive and definitely a lot easier than my first answer. Note, you need to verify the type of glass you have and make sure that the stuff you buy is compatible with with it.