I recommend you let a pro do it - they can do it with ease and it will be
nearly invisible. Most (all?) use the Novus franchise method, which involves
grinding away the debris like a dentist preparing to fill a cavity, then
applying a powerful vacuum (gotta get the air out!) with a device that lets
them suck acrylic type filler into it. Then they use a UV light to cure it
and scrape away the excess. There is a guarantee it won't crack, but I don't
recall the details. Some insurances will pay for the repair with no
deductible and no surcharge so they don't have to pay for a replacement
windshield later.

It used to be they would ask if the crack is small enough it can be covered
by a quarter, but the last time they asked if it could be covered by a
dollar bill. Different suction head, I guess.

Mike