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 coated; let marinate for 15 minutes.
In a separate shallow dish, combine the panko, almond flour, garlic powder, onion powder, paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, letting excess drip off, then dredge it thoroughly in the breadcrumb mixture, pressing firmly to adhere.
Lightly coat the air fryer basket with avocado oil and place the chicken inside; spray the top of the chicken with the remaining oil.
Air fry at 375°F for 12-15 minutes, flipping halfway through, until the internal temperature reaches 165°F and the exterior is golden brown.
While the chicken cooks, whisk together the Greek yogurt and hot sauce in a small bowl to create the spicy spread.
Toast the whole wheat bun until lightly browned.
Assemble the sandwich by spreading the yogurt sauce on the bun, then layering the lettuce, tomato, and crispy chicken.