Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness.
In a shallow bowl, soak the chicken in buttermilk for at least 15 minutes to tenderize.
In a separate small bowl, whisk together the flour, smoked paprika, garlic powder, onion powder, sea salt, and black pepper.
Remove the chicken from the buttermilk, letting excess drip off, then dredge thoroughly in the flour mixture until fully coated.
Lightly brush or spray the chicken with avocado oil and place in an air fryer basket.
Air fry at 375°F for 12-15 minutes, flipping halfway through, until the exterior is golden brown and the internal temperature reaches 165°F.
While the chicken cooks, lightly toast the whole wheat bun in a dry pan over medium heat.
Assemble the sandwich by placing the crispy chicken on the bottom bun, followed by the lettuce, tomato slices, and pickles, then top with the remaining bun.