I have a smart TV that's never spoken to the internet after exiting the factory, but it's a pretty tenuous state of affairs. I have this fear that someone staying over is going to see the "Services unavailable, press [menu] to troubleshoot" toast that shows up overtop the HDMI feed for a few seconds and think they're helping me by connecting it. 4-5 years worth of firmware updates all at once... half a decade of watch data somehow extracated from the HDMI feed and stored for precisely this moment... ads everywhere. Even if it doesn't happen instantly, I can only assume there's some flag deep in the OS called makeEverythingWorse just waiting to be flipped on the femtosecond The Beast catches a whiff of a slightly-higher patch number; now content in it's doomed state after having fufilled it's one true purpose of telling someone at samsung my favourite show is HDMI2.
I have had to back my mother down from that precipice on her own TV so I know it's worth worrying about. The siren call of an entirely empty TV homescreen beckoning us with a struck-out radio tower icon. "We have Disney+ and CraveTV too... press [menu]... pay no attention to the sticky note your son put on the coffee table"
I fear the same but made sure I block basically everything at the network level. First thing I do is hook the tv to the network and black hole its mac.
Find the TV’s MAC address and block it on your router. My brother home network had this system where your MAC address had to be whitelisted on the router to communicate with the network, as the days go by I see how in hindsight how this might be for the best in the end.
> I have this fear that someone staying over is going to
This happened to me. After they left, I tried a factory reset, but I don't have confidence there's not some code to remember previously saved wifi connections because my tinfoil hat is firmly in place. However, as you've said I only use the TV as an HDMI receiver. None of the TV's apps are used again. So I'm not sure how much they can detect from just the use of the HDMI port as the only thing being used. The games we play to get the subsidized pricing.