It's not a matter of "cheap", even the high end Sony TVs have spyware on them by default. The best thing you can do is get Claude or Codex to adb into your TV and uninstall all the malware, then keep it disconnected from Wifi and use an external box like Apple TV to watch.
Just disconnecting from Wifi often doesn't work because the TV will connect to insecure wifi to upload data and fingerprint what you're watching and who you are.
I don’t think that will help with the TV installing malware on your pc. Though to your point, Claude or codex could probably help with that too.
It made more sense when I first heard this theorized back in the early 2010s when smart TVs were becoming more common and unsecured WiFi hadn't vanished completely yet. Now it would be way more logical to include a cheap 5g radio, which has also been alleged but I haven't seen any model shown to include one.