I mean, people say use end to end encryption, VPN, Tor, Open Source Operating System, but I think one thing missed is the hardware is not really open source, and theres no practical open source alternative for hardware. There’s Intel ME, AMD PSP, so there’s probably one in phones. How can people be so confident these encryption is gonna stop intelligence agencies?
There’s no way to check the whole thing, but you can totally pick a component and reverse engineer it, which is something people do quite a bit. When spying is found, it’s usually a private company doing it.
The NSA doesn’t care about your search history, but advertisers do. (and the government ever did, they’ll just call up google)