I may get backlash for this, but I think 50 people is nuts for a 4 year old's bday party unless you have a large family or a long-standing group of kids your kid knows from several years at the school. J has been there like 3 months.
When our kids were in preschool we just had a few of their close friends and our family come over for a party. It wasn't until elementary school that we did the bigger parties, and those were usually at some birthday location. Even so, I wouldn't invite 50 people to our house for a 4 year old's bday and serve any main meal unless it was mostly our family - but that is me. For preschoolers you need snacks, snacks, and more snacks, easy to serve and eat foods, and the dessert(s). You can schedule the party at a time when a main meal isn't needed (2pm-4pm) and just serve appetizers, snacks, drinks, dessert. If you are doing food, pizza seems odd when you could just grill a ton of hot dogs and burgers and throw in a fruit platter and snacks, or just get some sandwich trays from Costco or Publix or something. J probably will only eat pizza.
There is no way I would spend the money on 20 pizzas on top of everything else for a preschool bday party. I forgot the Trackers are so cuntcierge.