Place the chicken pieces in a bowl and pour in the buttermilk and hot sauce. Stir to coat, cover, and refrigerate for at least 30 minutes or up to 2 hours. This tenderizes the chicken and gives it incredible flavor.
In a large bowl, whisk together the flour, cornstarch, smoked paprika, garlic powder, onion powder, chili powder, salt, and black pepper until evenly combined.
Working in small batches, lift the chicken pieces from the buttermilk and let the excess drip off, then toss them into the seasoned flour mixture. Press the coating firmly onto each piece and shake off any loose flour. For extra crunch, dip each piece back into the buttermilk one more time and press into the flour again.
Preheat the air fryer to 400 degrees F. Arrange the coated chicken pieces in a single layer in the basket, leaving a little space between each piece. Spray the tops generously with cooking spray.
Air fry for 8 to 10 minutes, shaking the basket halfway through, until the chicken is golden brown and cooked through with an internal temperature of 165 degrees F.
Serve the popcorn chicken hot with ranch, honey mustard, or barbecue sauce for dipping.