Preheat oven to 350F and move the rack to the top third of the oven.
Add olive oil in a large skillet on medium high heat. When the oil is hot, add the chicken. Cook for about 3-4 minutes per side, or until it's mostly cooked through. Turn the heat down if it really starts to splatter. Remove the chicken to a plate.
Add the pineapple juice, lime juice, tomato paste, garlic, and jerk seasoning to the pan. Shred the chicken with two forks, then add it back in the pan. Coat the chicken with the sauce and let it cook for 2-3 minutes.
Arrange a layer of tortilla chips on a baking sheet (use about half the bag - we'll be making 2 layers). Layer on about half the chicken, some pineapple, then about half the cheese. Repeat for the second layer, and then top with the jalapeno slices if using. Bake for 10-15 minutes or until the cheese is melted and they're cooked to your liking.
Meanwhile, prepare the avocado, red onion, remaining lime, sour cream, and cilantro.
When the nachos are done, remove them to a large plate (or keep them on the baking sheet... no one is judging), and add on the avocado, onion, lime, sour cream, and cilantro. Enjoy immediately.