Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness to ensure uniform cooking.
Submerge the chicken in the buttermilk and marinate in the refrigerator for at least 30 minutes to tenderize the meat.
In a shallow bowl, whisk together the almond flour, garlic powder, smoked paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, allowing the excess to drip off, and dredge it thoroughly in the seasoned flour mixture.
Lightly coat the air fryer basket with avocado oil and place the breaded chicken inside, spraying the top of the chicken with a tiny bit more oil.
Air fry at 375°F for 12 to 15 minutes, flipping halfway through, until the exterior is golden brown and the internal temperature reaches 165°F.
Lightly toast the whole wheat bun and assemble the sandwich by layering the lettuce, crispy chicken, and pickles.