In a small bowl, mix the mayonnaise, sour cream, one teaspoon of ranch seasoning, and pickle brine. Stir in the optional fresh dill, cover, and refrigerate.
Finely chop the dill pickles and drain off excess liquid.
Combine the ground chicken, one tablespoon of ranch seasoning, garlic powder, black pepper, and salt if needed. Mix gently until evenly seasoned.
Divide the chicken into eight equal portions. Spread each portion in a thin, even layer over one low-carb tortilla, pressing gently so the chicken adheres.
Heat a large nonstick skillet over medium to medium-high heat. Lightly grease it if needed.
Place a prepared tortilla in the skillet with the chicken facing down. Cook for approximately 3–4 minutes as a starting point, allowing the chicken to brown and release from the pan. Adjust the time for thickness and heat.
Check that the chicken reaches an internal temperature of 165°F (74°C). Carefully flip the taco so the tortilla side touches the skillet.
Sprinkle with cheddar cheese and cook for another 30–60 seconds, until the tortilla is lightly toasted and the cheese melts. Reduce the heat or cover briefly if needed.
Transfer the taco to a plate and repeat with the remaining portions, cooking in batches to avoid crowding the skillet.
Drizzle with the creamy pickle-ranch sauce, top with chopped dill pickles, and serve immediately.