Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness.
Place the chicken in a shallow bowl and pour the buttermilk over it, ensuring it is fully submerged; marinate for at least 20 minutes.
In a separate shallow dish, 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 thoroughly in the seasoned flour mixture until well-coated.
Lightly spray or brush the chicken with avocado oil and place it in the 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 lettuce on the bottom bun, followed by the crispy chicken and the dill pickle slices.