Combine the barbecue sauce, pineapple juice, soy sauce, garlic, ginger, and Sriracha in a large mixing bowl. Marinate the chicken in this mixture for at least 30 minutes or overnight.
Remove the chicken from the marinade and drain off any extra liquid. Spray the pineapple slices with cooking spray before grilling. Grill the chicken and pineapple for 4-5 minutes on each side, or until cooked through. To cook thinner chicken, decrease the number of sides on which it is grilled.
Meanwhile, reserve any extra marinade in a saucepan. Bring to a boil and simmer for 4-5 minutes until somewhat reduced. Serve chicken and pineapple with the remaining sauce.
