Actually, you could probably serve real pizza, as is, to turtles, and they’d eat it. That’s a thing about turtles. Once they settle in as your pets, and get used to being hand-fed, they’ll eat just about anything you offer them. And you have to take care because they’ll do it whether it’s good for them or not.
Every night my little painted turtle got a bit of my supper. And he’d climb out of his tank if he smelled lobster (those were the days!).