Roku TVs have had this from the start. When you first setup (or factory reset) the TV, you can choose to not connect it to a network. In that state, neither W

Roku TVs have had this from the start. When you first setup (or factory reset) the TV, you can choose to not connect it to a network. In that state, neither WiFi or Ethernet are routable, so no data leaves the TV. The TV does broadcast a private WifI network used for pairing RF remotes. Roku releases USB updates for the TVs periodically, usually a little while after a major release has been released over the network to all units, but those updates usually aren't needed for unconnected use unless there's some issue with OTA reception or HDMI that were found in the field.