Preheat a large skillet on medium heat. Add onions avocado oil, salt and pepper and let cook while preparing jackfruit. Shred jackfruit by pulling the pieces apart with your fingers or with forks, then add it to the pan. Stir and cook for 5 to 7 min, stirring occasionally until lightly browned. Add black beans, stir and set aside.
Meanwhile, add all Apple BBQ Sauce ingredients to a small saucepan and whisk together thoroughly. Bring to a boil, then lower heat and gently simmer for 10 min. Stir in most of sauce to the jackfruit-black bean mixture, reserving a couple tablespoons to serve with.
Whisk together all Slaw Dressing ingredients in a small bowl, then add it to the red cabbage, napa cabbage, carrots, and cilantro. Gently toss together, taste for seasoning, and add more salt and pepper if desired.
Assemble nachos by arranging tortilla chips across a small baking tray (or around ¾ of a large baking tray). Spoon jackfruit-black bean mixture across chips, followed by vegan cheddar and mozzarella. Place baking tray under broiler until cheese is melted. Remove from oven and spoon slaw over top. Top with jalapeno slices, fresh cilantro, lime wedges, hot sauce, and remaining Apple BBQ Sauce.