For the shrimp: Preheat the grill or the oven to 350 degrees F.
Prepare the pineapple and sauce. Slice the pineapple in half. Slice the core out of the center and discard. Cut out the flesh, leaving a 1-inch border all the way around. Finely chop two-thirds of the pineapple flesh and set aside in a bowl. Add the remaining pineapple flesh to a blender along with the BBQ sauce. Season with a pinch of salt and a few grinds of pepper, then blend until smooth.
Prepare the shrimp. Add the shrimp to an aluminum foil pouch (or create a pouch with aluminum foil), then sprinkle with salt and pepper and pour the pineapple BBQ sauce over the top. Close the pouch and place over the direct heat of the grill, or on the bottom rack of the oven. Cook until a quick peek inside reveals opaque shrimp, 10 to 12 minutes.
For the rice: In the bowl with the reserved chopped pineapple, add the rice, cilantro, scallions, zest and salt and pepper to taste. Stir to combine.
To serve: Divide and fill both halves of the pineapple with the rice. Remove the shrimp from the pouch and top both pineapple halves equally. Pour the juices from the pouch over everything. Top with the cilantro and serve with lime wedges for spritzing.