01 - Whisk together soy sauce, pineapple juice, brown sugar, ketchup, rice vinegar, ginger, garlic, sesame oil, honey, smoked paprika, and pepper in a large bowl until thoroughly combined.
02 - Measure out 1/2 cup of the marinade and transfer to a separate container for basting; set aside.
03 - Place chicken pieces in a large resealable bag or shallow dish. Pour remaining marinade over chicken, ensuring all pieces are evenly coated. Cover and refrigerate for minimum 2 hours, up to overnight for maximum flavor.
04 - Preheat grill to medium-high heat (400°F). Lightly oil grates to prevent sticking.
05 - Remove chicken from marinade and discard used liquid. Pat chicken pieces dry with paper towels.
06 - Grill chicken skin side down for 6-8 minutes. Flip pieces and grill additional 6-8 minutes.
07 - Brush chicken with reserved marinade. Continue grilling, turning and basting every 2-3 minutes until internal temperature reaches 165°F and surface is caramelized, approximately 20-25 minutes total grilling time.
08 - Remove from grill and let rest for 5 minutes. Garnish with scallions, sesame seeds, and fresh pineapple if desired. Serve hot.