Take the pork and trim any excess fat from it. Using a sharp knife, cut the pork into 1-inch cubes, removing any bones as you go.
Add the pineapple, juice, red onion, jalapeno and chipotle peppers to a food processor and blend until pureed. Place the pork cubes in a bowl or resealable plastic bag and cover it with the pureed pineapple mixture. Refrigerate and marinate for anywhere from 2 hours to overnight.
Preheat the oven to 425 degrees F. Add the pork to a baking dish along with the other cup of pineapple. Roast for 30 to 35 minutes, or until the pork reaches an internal temperature of 145 degress. Remove the dish from the oven and let the mixture cool slightly, just until it’s cool enough to work with. Shred the pork with 2 forks or throw it in your stand mixer and mix until shredded. Stir 1/4 cups of enchilada sauce and a handful (around 1/3 cup or so) of grated cheese into the shredded pork and pineapple.
Reduce the oven heat to 350 degrees F. Spray a 9×13-inch baking dish with nonstick spray. Spoon some of the enchilada sauce on the bottom of the dish, spreading it around. Spoon some more sauce on a separate plate. Take each tortilla and dip it in the sauce on the plate, running a spoon on both sides just so the tortilla is lightly coated. Add 2 to 3 tablespoons of the pork mixture in the center of each tortilla and roll it up, placing it in the baking dish. Once finished, spoon the remaining sauce (you can save a little for drizzling after if desired) over the enchiladas. Cover with the remaining cheese. Bake for 25 to 30 minutes. Serve with sour cream, fresh cilantro, extra pineapple and avocado.