Not sure about splitter without grilles but, I have the 1LE grilles (upper and lower) in my 2019 ZL1. No other stuff required, plug n play. They were paint matched Mosaic Black Metallic with an adhesion promoter. Came out nicely, just note the 1LE lower grille is dimple textured on the "fangs" so it looks like snake skin when painted. Enjoy.
https://www.camaro6.com/forums/showthread.php?t=567083