Combine smoked paprika, black pepper, garlic powder, onion powder, oregano, cayenne pepper, salt, buttermilk, and beaten egg in a spacious mixing bowl. Add the chicken pieces, ensuring they are fully submerged and coated. Cover with plastic wrap pressed directly onto the surface and refrigerate for at least 30 minutes, ideally up to 2 hours. Preheat the air fryer to 300°F. In a separate bowl, whisk together the flour, cornstarch, baking powder, salt, onion powder, and garlic powder. Remove each piece of chicken from the brine, allowing excess liquid to drip off, then dredge thoroughly in the flour mixture. Set each breaded piece aside. Generously coat the air fryer basket with cooking spray. Arrange the chicken in a single layer, ensuring the pieces do not overlap. Mist the tops of the chicken liberally with cooking spray. Air fry at 300°F for 20 minutes. Gently turn each piece over, taking care to preserve the crust, and spray the tops once more. Continue cooking at 400°F for an additional 15 to 20 minutes, or until the exterior is crisp and golden brown and the internal temperature reaches 160°F when tested at the thickest point without touching the bone. Resist the urge to snack on the crispy skin before serving — though if you do, forgive yourself immediately.