If using wooden skewers, soak them in water for at least 30 minutes.
In a large bowl, whisk together the barbecue sauce, soy sauce, pineapple juice, honey, garlic, smoked paprika, and black pepper.
Add the pork cubes and toss until evenly coated. Cover and refrigerate for at least 1 hour or up to 8 hours.
Preheat the grill to medium-high heat.
Thread the pork, pineapple chunks, bell peppers, and onion pieces onto skewers, alternating ingredients for color and flavor.
Lightly oil the grill grates.
Place the skewers on the grill and cook for 12 to 15 minutes, turning every few minutes.
Brush the skewers with additional barbecue sauce during the last 5 minutes of cooking.
Continue grilling until the pork reaches an internal temperature of 145°F and the pineapple is lightly caramelized.
Remove from the grill and let rest for a few minutes before serving.