Cut the chicken breasts into 1-inch chunks and set aside.
In a medium bowl, whisk together 2 cups water, 1 tablespoon kosher salt, and Worcestershire sauce until the salt dissolves.
Add the chicken to the brine, stir to coat, then refrigerate for 30 minutes.
While the chicken brines, combine flour, crushed panko, onion powder, 1 teaspoon kosher salt, pepper, garlic powder, and baking soda in a shallow dish.
In a second shallow dish, whisk the 3 egg whites until foamy.
Remove chicken from the brine and discard the brine; pat the pieces dry with paper towels.
Coat each chicken piece in egg white, then dredge in the flour-panko mixture. Place on a plate and let sit 10 minutes to help the coating adhere.
Recoat each chicken piece in the flour mixture, pressing the mixture onto the chicken with your fingers.
Heat peanut oil in a large Dutch oven over medium-high heat to 350°F (use a deep-frying thermometer to check).
Working in two batches, fry the chicken until golden brown, flipping once, about 3 minutes per batch total. Transfer to a wire rack set over a rimmed baking sheet to drain and keep warm in a 200°F oven if desired.
Whisk together mayonnaise, Dijon mustard, yellow mustard, honey, and cayenne pepper in a small bowl to make the dipping sauce.
