Does any country other than Poland serve a tomato-catsup-like sauce on the side with their pizzas?
Yes. I think it's safe to say that any pizzeria has a bottle of ketchup on the table.
Bacon Cheeseburger Pizza
Ketchup and Mustard base, covered in Hamburger, Monterey Jack, Cheddar and mozzarella Cheese, topped with Bacon $13.30/$16.55
If someone has a taste for this I'm sure the owner of Tony's Pizza in Cheektowaga, NY (suburb of Buffalo) will be thrilled.
I've been to the place a few times but never tried pizza with ketchup/
Hungarians are also know to serve ketchup with pizza.