Cut chicken into 1.5-inch uniform pieces.
Whisk together pickle juice, milk, powdered sugar, garlic powder, onion powder, smoked paprika, salt, and pepper.
Add chicken to marinade. Cover and refrigerate for 1 to 4 hours.
Remove chicken. Lightly pat dry and dust with extra salt and smoked paprika.
Preheat grill or grill pan to medium-high. Oil the grates.
Grill nuggets 3 to 4 minutes per side until internal temperature reaches 165°F.
Rest for 2 to 3 minutes off heat.
Mix mustard, honey, and mayonnaise for the dipping sauce. Serve alongside.