Breaded, fully cooked chicken nuggets, tenderloins and filets (whole muscle boneless breast pieces) are available from a number of producers. They may go through several processes, including marinating, pre-dusting, battering, breading, frying and/or oven baking and quick-freezing. Here's help on breading terminology from Perdue's online poultry school.
Breading pickup refers to the amount of coating that adheres to the chicken
Lightly breaded-Up to 14% pickup
Breaded-14 to 30% pickup
Fritter-30 to 64% pickup
Croquettes-64% and higher pickup
Homestyle-Process by which a fritter-breaded product is flipped around to replicate a hand-breaded appearance