With ethernet over HDMI being a thing, I've heard reports of TVs tunneling out through a media box without asking first.

That would require 2 Devices supporting Ethernet-over-HDMI, and one of needs to have routing/bridging enabled.

I have -up2now- not seen 1 device, where the combination of HW/SW was capable of offering ethernet to the Device OS.

AFAIK, no (mainstream) PC/Embedded/Mobile graphics chip/firmware/driver combination supports this. Please do indicate a counter-example, if you know of one.

I consider that unlikely to change too, since Ethernet is limited to 100Mbit over HDMI. Gigabit (Wifi) ate that lunch.

Outside of "Device-Collections" from e.g. B&O, that might use that comm-channel to have a "guaranteed communication backend" available, I see no real (commercially) interesting reason for implement it.

Having said that, I'd be very happy, if GFX-card/TV vendors started implementing the optional parts of the HDMI spec, like CEC,ARC, and Ethernet. I'd find use for it.

Ethernet-over-HDMI is so poorly supported in consumer devices that in HDMI 2.1 they dropped in completely and reused the pins for eARC audio.

My TCL bootloops if it doesn't have an internet connection. It also shows ads on its screensaver. Coincidence? Dunno, but it's sure making TCL money and making me miserable.

Can you factory reset it? I have a TCL Roku TV which I've never connected to the Internet and it shows a pretty standard 'logo bouncing around the edges of the screen' screensaver.

I sure can. I can even select a screensaver other than the "city with ads" one. Then it starts to bootloop until I reset it to defaults and connect it to the internet. Yes, I need to do both, or it starts bootlooping again. Support is all too happy to walk me through the process.