I'd call call Heartland Customer Service at 877-262-8032 / 574-262-8030. Have your VIN # ready. If Customer Service doesn't know, ask for Big Country sales. When you get the answer, circle back around to let everyone here know the answer.
Heartland got back to me and it's a Bluetooth speaker charging port. She stated there should be 2 of these and should have a cover with a QR code for purchasing the speakers. I only found 1 of them and that one is in the basement. Now we know.
That is kind of an odd product to try and push, and also a poor placement for the charger. If you wanted to actually use it, seems like you would need to leave a good amount of space open to get to it.