Well no, if the baseband firmware sends that then only the cell operator would see them, there's no user-controlled software or hardware between the chip and th

Well no, if the baseband firmware sends that then only the cell operator would see them, there's no user-controlled software or hardware between the chip and the mobile operator (like the router in the wifi scenario) unless you run your own 4G cell and record packets there. Just as for your laptop, if your ethernet firmware would be malicious in this way then it would apply only to the ethernet adapter and not any other network adapters like wifi.