Your average person isnt going to set up a pihole

It actually tries to connect to networks around you and if successful phones home that way.

It would locally store the logs forever and when you sell it or pass it on, that person might connect it to the internet which will send the backlog.

You can also disconnect the wifi/bt daughterboard.

I wouldn’t even hook it up to internet.

Depends on whether you can identify and cleanly block the traffic you don't want, while still allowing the traffic needed for the online services. I'd instead keep the TV offline and use an external streaming device (ideally something like Kodi, but more realistically a Google TV streamer or similar)