Preheat the oven to 350 degrees F (175 degrees C). Place biscuits 1 inch apart on an ungreased baking sheet.
Bake in the preheated oven until golden brown, 13 to 17 minutes. Set aside.
Mix buttermilk, egg, sriracha, salt, garlic powder, and cayenne pepper together in a shallow bowl. Mix flour and chicken and pork rub together in a separate shallow bowl. Dip chicken into buttermilk mixture then dredge in flour mixture; shake off excess.
Heat oil and butter in a cast iron skillet over medium heat. Fry coated chicken in the hot skillet until golden and cooked through, about 3 minutes per side.
Mix sriracha and agave nectar together in a bowl; adjust heat level to suit your preference.
Slice biscuits in half and place 1 piece of chicken on each bottom half. Place about 1 tablespoon sauce on each piece of chicken and top with the remaining biscuit halves.
