Genuinely no clue.

As I understand it if you want to have full trust on something, you’ll just have to channel your inner Richard Stallman and never use any tool you don’t fully understand. That means that to ensure your chips don’t have some insidious state surveillance backdoor you’d be mandated to not just have boards that have an open-source design… But to learn advanced electronic engineering so you could personally study those designs and ensure beyond doubt that they are secure.

That said maintaining a healthy distrust of any megacorp is a lot easier, if less guaranteed.