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 well combined.
02 - Measure 1/2 cup of the marinade and set aside in a separate container for basting during grilling.
03 - Place chicken pieces in a large resealable bag or shallow dish. Pour remaining marinade over chicken, ensuring all pieces are coated. Cover and refrigerate for at least 2 hours, up to overnight.
04 - Preheat grill to medium-high heat (400°F). Clean grates and lightly oil to prevent sticking.
05 - Remove chicken from marinade and discard used liquid. Pat chicken pieces dry with paper towels.
06 - Place chicken on grill skin side down. Cook for 6-8 minutes until skin is marked and crispy.
07 - Turn chicken pieces over and grill for another 6-8 minutes.
08 - Brush chicken with reserved marinade. Continue grilling, turning and basting every 2-3 minutes until internal temperature reaches 165°F and glaze is caramelized, approximately 20-25 minutes total.
09 - Transfer chicken to a platter and let rest for 5 minutes. Garnish with scallions, sesame seeds, and fresh pineapple if desired. Serve hot.