For the chicken: Preheat the oven to 425 degrees F. Set a wire rack in a rimmed baking sheet and spray the rack with nonstick spray. Set aside.
Combine the mayo, mustard, Parmesan, garlic powder and a few turns of pepper in a large bowl. Add the pretzels to a separate bowl or large shallow dish. Coat the chicken all over in the mayo mixture, then the crushed pretzels, and transfer to the wire rack, spacing it out evenly. Spray the chicken with cooking spray and bake until fully cooked, with an internal temperature of 165 degrees F, 12 to 18 minutes.
For the dressing: Combine the yogurt, Parmesan, oil, mustard, Worcestershire, pepper, salt, garlic, lemon juice and zest in a bowl and adjust the seasoning as needed.
For the salad: Toss together the kale, Parmesan and radishes in a large bowl. Top with the avocado slices, chicken and more shaved Parm as desired.