Toss chicken pieces with 1T kosher salt. Transfer to a bowl; cover and refrigerate overnight.

Whisk buttermilk, pickle brine, hot sauce, and egg together in a mixing bowl. Pour marinade over chicken and stir to coat each piece thoroughly. Cover and let chicken marinate in refrigerator for 24 hours.

Mix flour and salt together in a shallow flat dish. Remove chicken from marinade and blot with paper towels. Reserve marinade. Toss chicken in flour until thoroughly coated. Return chicken to marinade, coating all sides; remove chicken from marinade allowing excess to drip back into the bowl. Coat the chicken once again in the flour mixture. Place on a rack. Repeat with all pieces. Allow to sit out for 15 minutes to allow coating to dry out a bit.

Place butter and lard in a large pot. Add cayenne, brown sugar, paprika, garlic powder, kosher salt and black pepper. Place over medium-high heat. Cook and stir until fats melt. Remove from heat; keep sauce warm.

Fill cast iron skillet about 1/3 of the way with oil. Heat oil to 350° over medium-high heat. Carefully place chicken in the hot oil, skin side down. Keep the oil temperature at 325°, adjusting if needed. Fry until internal temperature is 160°, 8-10 minutes per side.

Transfer the chicken to a rack to drain. Brush with the sauce on both sides.