Rub the pork shoulder all over with the spice mixture, pressing it into the meat to coat evenly.
Place the seasoned pork in the slow cooker and pour in the broth or water around it.
Cover and cook on low for about 8 hours, until the pork is tender and easily pulls apart with a fork, filling your kitchen with smoky, spiced aroma.
Once cooked, carefully transfer the pork to a large bowl and shred it using two forks, letting the juices soak into the meat for maximum flavor and juiciness.
Mix the shredded pork with barbecue sauce to coat evenly, enhancing the smoky flavor with sweetness and richness.
Preheat your oven or broiler and layer a generous handful of tortilla chips on a baking sheet or oven-safe dish.
Spread a portion of the saucy pork over the chips, then sprinkle with shredded cheese and sliced onions and peppers if using.
Repeat the layering process to build a hearty pile of nachos, finishing with a generous cheese layer on top.
Bake or broil until the cheese is melted and bubbly, about 5 minutes, and the edges of the chips are crisp.
Squeeze fresh lime juice over the nachos for a bright, citrusy finish and serve hot with your favorite toppings.
