HDMI ethernet channel is a thing, though semi-obsolete. It's unusual for a PC graphics card to support it. Intel website suggests they don't support it: https://www.intel.com/content/www/us/en/support/articles/000...
Why is not connecting your TV to wifi asinine? Generally works fine but I suppose there are rumors that some TVs scan for open networks and connect to them automatically.
The only solution I suggest is physically removing WiFi cards from the guts before turning on.
It's going to be very unusual to find a TV using removable PC components like wifi cards. Another option is to connect it to your network but block it from the internet