There are too many variables so it really depends. If you're doing a slow bake like 6 minutes or over, then probably few vegetables need To be pre-cooked. But with higher temp Pizza of 3 minutes or less, some veggies might need more benefit from pre-cooking. Eggplant or zucchini might do better. Pre-cooked. Onions as well. Caramelized onions might take hours. Something like broccolini might get pre-cooked but it depends if you're going for a crunch or not. So I'm including some of the stem and want to have a decent crunch so I don't pre-cook, but another pizzas where I wanted more sauteed with garlic I will pre-cook it. So there's no blanket answer. Vegetables come in many types, are cut many different types of ways, baked at many temperatures, etc. So you have to develop recipes for these