Heat 1/4 cup oil in a large skillet over medium heat until hot but not smoking.
Beat 2 large eggs with 1 teaspoon water in a bowl and set aside.
Place 1/4 cup whole wheat flour on a small plate for dredging.
In a mixing bowl combine 1 cup whole wheat panko, 1/2 cup grated Parmesan, 1 teaspoon kosher salt, 1 teaspoon chopped rosemary, 1/4 teaspoon garlic powder, 1/4 teaspoon onion powder, 1/2 teaspoon paprika, 1/4 teaspoon chili powder, and 1 teaspoon lemon zest; mix well.
Cut 1 1/2 pounds chicken into 1-inch cubes.
Working in batches, lightly coat chicken pieces in flour, shaking off excess, then dip into the beaten egg and let excess drip off.
Roll the egg-coated chicken in the panko-Parmesan mixture until fully covered; repeat for remaining pieces.
Add a few coated chicken pieces to the hot oil, cook about 5 minutes per side until golden brown and cooked through (internal temperature 165°F), then transfer to a paper towel-lined plate; repeat with remaining chicken.
Serve the nuggets immediately with honey mustard or marinara, if desired.
