That Pompeii fresco could never have been pizza as we think of it. Sure, humans have put stuff on breads since bread was first made because bread alone is boring. It probably was like focaccia with stuff on it. No tomato or mozzarella though. Maybe fruit, oil, herbs.
Pastry stuff less boring, as in our galette post yesterday. Looks like a pizza.
While the typical Italian-American "tomato pie" is what Americans tend to think of, pretty much anything can be cooked on a pizza crust. In Southern Italy and Sicily, the menu will have 40-50 choices, most without tomato. Consider figs with goat cheese.
Or, in my photo from Sicily, egg and olive with pureed red pepper.