I would cut off the chewed part and, after thoroughly cooking, eat the rest. Rodents don't "poison" entire vegetables by chewing on them. Foodborne disease is transmitted through saliva, urine, and droppings. No way to know if a rodent didn't pee, poop, or drool on your veggies in any case. There is an "ick" factor, but you won't die from that. Oh, wash your hands after picking and cutting. But you do that anyway, right?

Is this vole, mouse, rabbit?

I doubt if it were a small critter like a vole or mouse, might be a rabbit if you have those in your location, or perhaps a groundhog?

Could definitely be a mouse! I only discovered I had an indoor mouse issue when I discovered some stored potato in my pantry gnawed away in a very similar manner. Since I have both a dog and a cat, I was surprised and pretty creeped out and promptly bought an old fashioned mousetrap, baited it with peanut butter and caught the little bugger!! I have since found my dog staring at one climbing up the outside of my screen door so I know they are out there. Outside I don't mind but indoors is not acceptable!!

Gopher? I had the little buggers make a hole directly under the squash and munch away unseen by the Coyotes that patrolled the area.