OTOH, if you're doing something that the intelligence agencies (regardless of country) is interested in, your only real hope is to use the the 100% open software/firmware like the FSF advocated
The question is, are you trying to stay off the radar, or trying to avoid having the NSA hack your computer once you're on the radar?
If the former, the challenge is that they can miss and miss and miss, and only have to hit once. You have to hit every time. The odds of that over any period of time are nearly zero. A single mistake and all your efforts are for nothing.
If the latter, no amount of electronic protection is going to do you any good. If they really can't hack their way in, they'll just wait until you leave for lunch and physically break in and copy your hard drives.
And if that fails and you're really on their radar, they'll just use rubber-hose cryptography. Very, very few computer people would stand up very long to a real honest-to-god gun put against their head.
And if that really does fail, there is always your family.
I might resist (at first) if they just threaten me, but I have 3 kids, put a gun to their heads and I'll do whatever I'm told. 99.9% of everyone will.