Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness.
In a small bowl, submerge the chicken in buttermilk and let it marinate for at least 20 minutes to tenderize.
In a separate shallow dish, whisk together the flour, garlic powder, onion powder, smoked paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, letting the excess drip off, then dredge it through the flour mixture, pressing firmly to create a thick coating.
Lightly brush or spray the coated chicken with avocado oil to help it crisp up in the air fryer.
Place the chicken in the air fryer basket and cook at 375°F for 12-15 minutes, flipping halfway through, until the exterior is golden brown.
During the last 2 minutes of cooking, place the biscuit in the air fryer to warm through until it is soft and flaky.
Serve the crispy buttermilk chicken immediately alongside the warm biscuit.