I don't think that's the same. Amz Sidewalk is very slow, low bandwidth over sub-GHz. What GP is thinking about is probably along the lines of, if not getting Internet access by the owner, willy-nilly connecting to any open wifi network it finds, and uses that.

But "meshing" with other apparatus from the same manufacturers is a clever and evil idea - perhaps another TV from the same brand is in range and has Internet, then they can proxy that way.

All these probably break some regulations or laws.

I tried searching for it, without much luck. I don't think I was thinking of Sidewalk, though. It was more like some TV manufacturer like TCL, LG, etc. The best I could find are some unconfirmed reports of devices automatically connecting to open WiFi, which doesn't quite match.

But I can't find anything now, so it might be best to consider it apocryphal.