Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness.
In a shallow bowl, whisk together the buttermilk, garlic powder, smoked paprika, sea salt, and black pepper.
Place the flour in a separate shallow dish.
Dip the chicken into the buttermilk mixture, ensuring it is fully coated, then dredge it through the flour, shaking off any excess.
Heat the avocado oil in a non-stick skillet over medium-high heat.
Add the chicken to the skillet and cook for 5-6 minutes per side until the exterior is golden brown and the internal temperature reaches 165 degrees Fahrenheit.
While the chicken cooks, lightly toast the whole wheat bun in a toaster or under a broiler.
Spread the Greek yogurt on the bottom half of the bun, then layer with the romaine lettuce.
Place the cooked chicken on top of the lettuce, add the dill pickles, and cover with the top bun.