Add shrimp, pineapple juice, juice from 1/2 lemon to a bowl. Season with salt, pepper and red pepper flakes and set aside. For best results marinate the shrimp for at least 30 minutes.
Preheat oven to 450F degrees. Line a baking sheet with foil or parchment paper.
Drain juice from shrimp completely. Transfer shrimp to lined sheet pan. Add the pineapple chunks, bell peppers, broccoli florets. Season with salt and pepper to taste.
Bake for 10-12 minutes. If needed broil for 1-2 minutes.
Squeeze juice from other 1/2 of the lemon onto the shrimp and garnish with fresh cilantro. Serve over rice.