Why is Xfinity Mobile not providing service for iPhone users with the iWatch 3 cellular?

I have been getting conflicting answers about the Xfinity Mobile and iWatch 3 with cellular. when I ordered / purchased my iPhone X the local office staffer told me that when my phone came in to bring it and the watch to the office ans she would help my activate the phone, transport my number and pair to my iWatch 3 (I had purchased it a week before). I activated over the phone as bad weather just kept me in. Thia was easy. And there I was told they did not connect iWatch 3. From this point I have asked via a tech chat, by Facebook where the responder says they are part of corporate. I am not deterred in my intention to ask at the official corporate level about this if there is no other way to get a clean straight answer.

One person from Comcast / Xfinity says it is coming later but has no idea when later is. Another says never. And that Xfinity will never connect service to a device they did not sell. (I call this one the greed effect). There have been a couple responses in between these extremes.

What is APPLES role in this? What is the underlying carrier's role on this? Has anyone been told that the Watch 3 would be supported as it is so for the 4 major carriers. If Xfinity Mobile does not offer support for the watch, they are setting the company not to be competitive with the major carrier for the Apple tech savvy users - we are.

I would like to hear from others who have this interest and have asked for or about this service to share the number on iPhone and iWatch 3.

I know I can connect by bluetooth and I do. That is not what I am after. I want to leave my phone locked away safe while working out and in case of a fall or serious health emergency when my phone is too far away to get to / connect via bluetooth or WiFi it.