I think CPU backdoors are just a theoratically possible thing with almost zero chance of happening or succeeding without anyone noticing or having massive consequences and would bring massive changes to the industry like open source makers sprouting up (because it would open up a market where the open aourc chips could be profitable) because if snapdragon really could do that i don’t think china will make phones with them . Also its not worth it because everything you could ever want could be scooped from users os/apps/sites and is far much easy/profitable/easier to get out scot free etc . Anyways i could be wrong about everything so take it with a grain of salt and feel free to correct me .