Never connect it, use external box
Buy any TV, never give it network access, and drive it over HDMI from a device you trust such as an Apple TV, mini PC or Linux box.
Physically remove or root
Some go further by unplugging the Wi-Fi module, stripping apps via adb, or rooting LG webOS sets to kill telemetry.
Open-Wi-Fi exfiltration is unproven
Skeptics say claims that TVs join open networks or Xfinity hotspots would be trivial to test and lack evidence, while others argue disabling hardware is cheap insurance.