Alternately thread the nuggets, red pepper and pineapple onto wooden skewers. Brush barbecue sauce all over the skewers. (Skewers can be stored, tightly covered, in the refrigerator for up to 3 days.)
Lightly coat a large, nonstick grill pan or skillet with cooking spray and set over medium heat. Warm the skewers, turning as needed and brushing with additional barbecue sauce, until heated through and well glazed. Serve with guacamole and/or sour cream on the side (if using).