In a large bowl, combine buttermilk, hot sauce, 2 teaspoons salt, and 1 teaspoon garlic powder. Whisk until well mixed. Add the chicken pieces, ensuring they're fully submerged. Cover with plastic wrap and refrigerate for at least 4 hours, but preferably overnight (up to 24 hours).
About 30 minutes before cooking, remove the marinating chicken from the refrigerator to take the chill off. In a large bowl or paper bag, combine all coating ingredients (flour, paprika, salt, black pepper, garlic powder, onion powder, cayenne pepper, thyme, and oregano) and mix thoroughly.
Pour oil into a large, heavy-bottomed cast iron skillet until it's about 1/2 to 3/4 inch deep. If using, add the bacon fat. Heat the oil to 350°F (175°C).
Remove chicken pieces from the buttermilk mixture, allowing excess to drip off. Place chicken pieces, one at a time, into the flour mixture, pressing firmly to ensure an even, thick coating. Shake off excess flour. For extra crispiness, let the coated chicken rest on a wire rack for 5-10 minutes before frying.
Carefully place chicken pieces skin-side down into the hot oil, working in batches to avoid overcrowding. Start with thighs and legs as dark meat takes longer. Maintain oil temperature between 325-350°F. Fry for 7-10 minutes per side, until deep golden brown and internal temperature reaches 165°F for breast meat and 175°F for thighs.
Transfer fried chicken to a wire rack set over a baking sheet. Let rest for 10 minutes before serving to allow juices to redistribute throughout the meat.