Slice each chicken breast in half horizontally to make 4 cutlets. Pound to an even 1/2-inch thickness.
Whisk the buttermilk, hot sauce and salt. Add the chicken and refrigerate for 30 minutes to 4 hours.
Whisk all the sauce ingredients together and refrigerate.
Whisk the flour, cornstarch, seasoned salt, garlic powder, onion powder, paprika, black pepper and cayenne in a shallow bowl.
Dredge each cutlet in the flour, dip back in the buttermilk, then dredge in the flour again. Rest 5 minutes.
Preheat the air fryer to 380°F for 3 to 5 minutes.
Spray the basket, add the chicken in a single layer, and spray the tops well. Air fry 12 to 15 minutes, flipping and spraying halfway, until 165°F inside.
Butter the buns and toast at 350°F for 1 to 2 minutes.
Spread sauce on the bottom buns, add the chicken, more sauce and pickles, and top with the buns.
Optional: Wrap in foil for 2 to 3 minutes for a soft, hot-case-style bun.