Spicy Shrimp Fajitas with Grilled Pineapple Pico

Name: Spicy Shrimp Fajitas with Grilled Pineapple Pico
Ingredients: 1 pound large shrimp, preferably wild (about 24), peeled, deveined, and tails removed; 1 tablespoon chipotle-in-adobo sauce (from a 7-ounce can); 1 packed teaspoon grated lime zest and 2 tablespoons fresh juice, plus 1 more lime, halved; 2 tablespoons extra-virgin olive oil, plus more for brushing; Kosher salt and freshly ground pepper; 1 medium white onion, cut into ½-inch rounds; ½ medium pineapple, cored and cut into ½-inch rounds; 8 flour or corn tortillas (each 6 inches); ⅓ cup packed chopped cilantro, plus sprigs for serving; Avocado slices and sour cream, for serving