I have seen before you can add this into the radio channels already in the vehicle and it plays known stations: Capital, Heart, Kiss etc.. I do not know how this would work with a police vehicle as the hot key for Lights on controller is the same. Although in Civ cars it could work.
I would struggle to listen to a radio station when we have radio comms, text chats and in game voice to contend with. Not including if you are in a Discord VC.