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.