I am not sure what the rule is on this, but I think that if everyone in the driverstation has wired earpieces to just each other it could be legal. I have thought about doing it to help me hear the coach. I am not sure what this guy used it for, but he did have headphones in, but they did not seem to be connected to anything other than a phone.
https://www.youtube.com/watch?v=-jd32B0chAg&t=242s