Whisk 2 tablespoons mayonnaise, 2 tablespoons yogurt, 1 tablespoon chili sauce, 1 teaspoon honey and 2 teaspoons Sriracha in a small bowl until combined. Set aside.
Whisk ⅓ cup buttermilk, ¼ cup cornstarch, ½ teaspoon garlic powder, ½ teaspoon onion powder, ½ teaspoon pepper and ⅛ teaspoon salt in a large bowl until combined. Stir in 1 pound shrimp.
Heat ¼ cup oil in a 12-inch nonstick skillet over medium-high heat until shimmering. Working in 2 batches, remove the shrimp from the batter, letting excess drip off. Arrange the shrimp in a single layer in the pan. Cook, flipping once, until pink, cooked through and browned on each side, 4 to 6 minutes. Transfer to a paper-towel-lined plate.
Transfer the cooked shrimp to a clean plate. Drizzle with 2 to 3 tablespoons sauce and the remaining 1 teaspoon Sriracha. Sprinkle with 2 tablespoons chopped scallion. Serve with the remaining sauce.
