Place the chicken breast between two sheets of parchment paper and pound with a mallet until it is an even half-inch thickness.
In a shallow bowl, soak the chicken in the low-fat buttermilk for at least 15 minutes to tenderize the meat.
In a separate small bowl, whisk together the whole wheat flour, smoked paprika, garlic powder, sea salt, and black pepper.
Remove the chicken from the buttermilk, letting any excess drip off, then dredge it thoroughly in the seasoned flour mixture.
Lightly coat the air fryer basket with half of the avocado oil, place the chicken inside, and spray the top of the chicken with the remaining oil.
Air fry at 400°F (200°C) for 12 to 15 minutes, flipping halfway through, until the coating is golden brown and the internal temperature reaches 165°F.
Lightly toast the whole wheat bun in a dry pan or the air fryer for 1 minute until warm.
Assemble the sandwich by placing the lettuce on the bottom bun, followed by the crispy chicken, dill pickles, and the top bun.