Yeah, this is certainly already a problem.

I trust Apple for a number of reasons, but I really had to be really aggressive about the TV it’s connected to.

But also, a smaller footprint is a smaller footprint. I’ll take “better” where I can get it.

Today, just don't connect your smart TV to a network, and you should be fine. (Assuming there's no open/passwordless WiFi networks nearby.)

If/when devices start shipping with cellular modems and eSIMs... honestly not sure. Faraday cage? Physically remove the modem? (If that doesn't prevent the device from booting.)

..: Surely the specs (or … whatever compliance paperwork, CE etc?) of the device have to state if it includes a modem or not?

If it does then don’t buy it?