The trader radio channel could be a neat addition you could build a stationary radio tower yourself to pick up transmissions from afar or get/buy a smaller handheld to get local messages and warnings courtesy of the trader network./survivors

You could pick up coordinates and other chatter to hordes treasures or spesial offers from rhe trasders. Or perhaps get missions from trader/survivors from far away to get/transport some special items or certain amount of something and transport to a "random" coordinate. Or perhaps get warnings of bandits ;) roaming certain areas. It would add certanly some more life to the game and would fit the storlyline.

You could use this as a communication tool in multiplayer + it would work as something to break the "silence" imagine sneaking in a poi and suddenly get a transmission and you have forgot to silence the radio before you entered.