That concept is not especially new, there have been historical HN posts about using microphones to listen to see if you are muting the commercials or not. Similar to this user tracking, my building recently installed ButterflyMX door entry, which not only tracks when you go in and out and sells that for advertising, but tracks you and your friends across properties to find connections between people.

Still, and while I find both extremely inappropriate, hardware backdoors are in another class. Nvidia's ambitions for remote disabling and charging rent to use keep using GPUs are more unsettling to me than a smart TV I can just simply not connect to the internet.