Sheet Pan Shrimp Fajita Tacos

Name: Sheet Pan Shrimp Fajita Tacos
Cuisine: American, Mexican, Latin American, TexMex
Ingredients: 1- pound mini bell peppers (stem removed and thinly sliced into rounds); 1 cup halved and thinly sliced red onion (½ large onion); 1 serrano pepper (stem removed and thinly sliced into rounds (optional)); 4 tablespoons avocado oil (divided); 2 teaspoons Kosher salt (divided); 1 teaspoon freshly ground black pepper (divided); 1 ½ pounds peeled (deveined and tail-off shrimp (36/40)); 2 teaspoons chili powder; 1 teaspoon garlic powder; 1 teaspoon smoked paprika; ½ teaspoon ground cumin; 1 tablespoon finely chopped fresh oregano leaves; Zest of ½ lime; 10 flour tortillas; 2 avocados (mashed); ¼ cup freshly chopped cilantro leaves; Salsa (for topping); 1 lime (cut into wedges)