For the Hawaiian pulled pork: Preheat the oven to 275 degrees F.
Mix the onion powder, garlic powder, 2 teaspoons salt and 1 1/2 teaspoons pepper in a small bowl. Rub the mixture on all sides of the pork. Combine the pineapple, hoisin, honey, soy sauce, vinegar, and 1 cup water in a Dutch oven. Add the pork and bake for 6 hours (alternatively, cook the pork in a slow cooker for 8 hours on low).
Shred the pork with 2 forks, removing any large pieces of fat. Return to the Dutch oven and stir to incorporate with the sauce.
For the cauliflower crust: Increase the oven to 400 degrees F. Line a baking sheet with parchment paper.
Break the cauliflower into florets and pulse in a food processor until fine. Steam in a steamer basket and drain well. (I like to put it on a towel to get all the moisture out.) Let cool.
Combine the cauliflower with the mozzarella, Parmesan, oregano, garlic powder, eggs and 1/2 teaspoon salt in a bowl. Transfer to the center of the prepared baking sheet and spread into a circle, resembling a pizza crust. Bake until brown and crispy around the edges, about 20 minutes.
Top the pizza with 1 1/2 cups pulled pork, the fresh pineapple and mozzarella and bake until warmed through and the cheese is melted, about 10 minutes more.
Garnish with pickled red onions and cilantro.
Pickled Red Onions:
Put the onions in a nonreactive heatproof bowl. In a small saucepan over medium heat, combine the bay leaf, vinegar, sugar, 1/2 cup water, 1 teaspoon salt and 1/4 teaspoon pepper. Bring to a low boil and allow the sugar to dissolve. Pour over the onion and let stand about 20 minutes. Remove the bay leaf and drain the onion, discarding the liquid.