Pat the pork very dry with paper towels. In a small bowl, stir together the kosher salt, black pepper, smoked paprika, garlic powder, onion powder, cumin, and smoked salt if using. Rub the seasoning mixture thoroughly over the pork shoulder. Let the pork sit at room temperature for 30 minutes before cooking.

Heat the olive oil in a large skillet over medium-high heat. Sear the pork on all sides until deeply browned, about 3–4 minutes per side. Transfer the pork to the slow cooker.

In a mixing bowl, whisk together the guava jam, barbecue sauce, ketchup, apple cider vinegar, Worcestershire sauce, soy sauce, Dijon mustard, lime juice, lime zest, chipotle powder, smoked paprika, garlic, and brown sugar. Add the molasses, chipotle hot sauce, or liquid smoke if desired.

Pour the chicken broth into the slow cooker. Add HALF of the guava BBQ sauce over the pork and reserve the remaining sauce for later. Cover and cook on LOW for 8–9 hours or HIGH for 5–6 hours until the pork shreds easily.

Transfer the cooked pork to a cutting board and let it rest for 10 minutes. Shred the pork using forks or meat claws. Skim excess fat from the cooking liquid in the slow cooker. Return the shredded pork to the slow cooker and stir in the reserved sauce. Add only 2–4 tablespoons of cooking liquid if needed for moisture. Cook uncovered on LOW for 15–20 minutes until glossy and lightly sticky. Finish with a squeeze of fresh lime juice and adjust salt if needed.

In a bowl, combine the green cabbage, purple cabbage, carrot, mayonnaise, apple cider vinegar, sugar, red onion, celery seed, salt, and pepper. Toss until lightly coated and chill until ready to serve.

Lightly butter the buns and toast until golden brown. Assemble the sandwiches by layering slaw onto the bottom buns followed by the pulled pork, pickles, red onion, and cheese or pineapple if desired. Serve immediately with fresh lime wedges.