I don’t think you’re understanding how trivial this is to detect:
Set up an open WiFi network in an area without any other open WiFi networks. i.e. almost anywhere outside of dense urban areas. Then you don’t even need to inspect traffic, just look at connected devices in admin controls. No devices should be connected aside from your monitoring device.
There’s no way the TV manufacturers are going to risk the legal quagmire that would come from this when there’s no plausible way to keep it remotely secret.
Isn’t it getting harder to find custom ROMs, now? Used to be basically everything was on XDA forums, but I’ve heard lots of custom ROMs are moving to they’re own websites/Discord servers/whatever.