For now, setting up an IoT network is pretty much best practice, and I'd wager the average Hacker News reader both has the necessary equipment and skills to do it. That may not always be the case.

Assuming they install some 5G modem in the device, which is pretty much dirt cheap these days (our local water utility uses 5G for meter readings, and the cost per meter is something like $1/year), there's literally nothing short of a faraday cage you can do.

The can report on what you watch freely, and only consumer laws can stop them. However, without a wifi connection they can't snoop on your local network, and they probably can't connect the data to you, assuming you don't register the TV for those 3 months of added warranty or whatever they try to get you to register.

I tend to avoid devices that are built to snoop on you, so no Amazon Alexa, no Google Home, no Apple HomePod. Everything I have utilizes local control via Home Assistant, and most of it is actively blocked in the firewall from accessing the internet. It's not hard to implement, and doesn't require a master of IT, but it does remove a lot of the convenience, which I guess is the reason people don't do it.