In a large bowl, mix pineapple juice, barbecue sauce, low sodium soy sauce, sesame oil, brown sugar, garlic powder, red pepper flakes, and onion powder to make a marinade. Set 1/4 cup of your marinade mixture aside.
Grill marinated pineapple and chicken breasts on medium-high heat for about 4-5 minutes on each side. Serve hot with extra marinade and optional green onion garnish.