Mix rice up with tomato sauce, melt a bit of mozzarella cheese in, some slices of pepperoni in it, sprinkle in some basil and oregano... check behind you that nobody can see you commit culinary crimes... delicious.
Completely different dough in terms of consistency and taste. Bread and pizza are quite different, so many ingredients that work on pizza don't work on sandwiches and vice versa.
Having said that, people can eat what they please.
Mayonnaise on pizza is surprisingly common in Finland, e.g
one local pizzeria near me puts garlic mayo on certain pizzas – enough that there's more mayo than tomato sauce. For some incomprehensible reason they also put the mayo under the cheese. As you can guess, it was repulsive. However, BBQ sauce and bacon pizza is a nice combination, which is also normal here.
Truffle mayo did work in some pizzas, in moderation.