In a medium bowl, combine the mayonnaise, sweet chili sauce, sriracha, and lime juice. Mix well and set aside.
In a separate bowl, pour the buttermilk over the shrimp and let it marinate for at least 15 minutes.
In another bowl, whisk together the flour, paprika, garlic powder, onion powder, salt, black pepper, and cayenne pepper.
Remove the shrimp from the buttermilk, allowing excess to drip off. Dredge each shrimp in the flour mixture, shaking off any excess.
Dip the coated shrimp back into the buttermilk and then coat with panko breadcrumbs, pressing gently to adhere.
In a large skillet, heat about 1 inch of vegetable oil over medium-high heat. Once hot, carefully add the shrimp in batches, frying for 2-3 minutes on each side or until golden brown and crispy.
Remove the shrimp from the oil and place them on a paper towel-lined plate to drain excess oil.
Toss the fried shrimp in the prepared sauce until well coated.
Serve immediately, garnished with chopped green onions.