That's a good idea. The canopy breaker tool for the F-106 worked like that (see image below--normally painted red and kept in a set of clips on the left side of the cockpit). The breaker tool for some other military aircraft was a striking tool with a curved chipper blade, which I think would be less effective.I have a small crescent wrench for snapping a hole with progressive bites, starting at the vent and chipping out as needed. I don't think the hammer will work as well.
The F-106 model is below.