Add line for onboard nav system

I finally got a chance to stop in at an Xfinity store and was told the answer to my question is Yes. He said the line would provide an Internet connection but no phone, which I didn't understand but I wouldn't use a phone number anyway. I expect he was as knowledgeable as anyone I might reach through Chat.

The manufacturers of these head units wouldn't provide cellular capability unless at least some providers were willing to support them, so I'm going to hope Xfinity is among them. This might be an Android head unit-only issue; I believe mainstream head units require a phone always to be present for CarPlay or Android Auto, whereas Android head units are independent devices that can either support CarPlay or Android Auto or operate on their own. I'm still learning about them.