My first (legitimate) job EVER was with Dominos Pizza, so I know what the hell I am talking about, since I worked in a store that sold over 300 pizzas in one hour uring a typical lunch day.
I've eaten every combination of pizza imaginable as whatever as sent back or didn't get picked up was free fare for the staff. I also held the record for most dough trays carried from the walk-in freezer in one trip (28, eight dough balls per tray) for almost 2 years. And so...
...Pineapple on pizza is totally allowable. Pineapple + Ham (Canadian Bacon) is what is typically referred to as "Hawaiian" pizza and is still very popular here in the USA, especially in the summer. Hawaiian ad Salami sounds pretty damn good too, the mushrooms, of course, mushrooms with anything are good. Zuchinni? Well, maybe after a few Cape Cods.
All you close minded pizza sissies better yank back your reservations about being open-minded to modern day bastardizations of the good-ole Italian pie. BTW, Grilled chicken and apples is AWESOME on pizza. So there.
OVM, you are a culinary mind that is ahead of this forum's culinary expertise, plow forward, Sir.