I've seen so many random industrial devices and parts come into our plant that have their own cellular it's wild.
In a television it's an added cost and it's unclear if serving ads really can offset that extra $25-100 of hardware (and included data) you ship on a $200-1000 television.
It's also unclear to me if the low data packages they come with would be enough to serve meaningful ads to begin with. Those devices usually come with a fixed plan of 100MB/month for 5yrs (or along those lines). Modern smart tv ads are very often video or at least hi res images.
Well... most TVs already have a WiFi/BT chipset for stuff like advertisements or, especially with Apple, high-bandwidth video streaming. There is already a radio module present, but (IIRC) you don't have to disclose what exactly that module is capable of.