On subject of CPU, I wonder how viable it would be to design usable CPUs at the component level. I would not be against the idea of going back to physically larger machines if it meant more privacy. Ex: 4U cases where you insert long cards in it. Could go to a computer platform that is based on cards, you have CPU cards, ram cards, various expansion cards etc. Chassises could be chained together to build more powerful machines too. The cards would have tons of transistors and other jelly bean parts and mostly be simple. Once the design is made it would be super cheap to whip these out in the millions. Go back to proper coding and micro optimization of code, and even if you can only do like 100Mhz or so due to physical size you could grow parallel instead. So you want a beefy computer, then you just insert more of those CPU cards. You want a computer with tons of ram, but don't need as much cpu, then insert more ram cards. Could be fully modular and all based on mostly jelly bean parts. Maybe some microcontrolers and stuff too for certain functions. FPGAs might also be an option but as someone said earlier I think those are fairly closed too, could easily be a backdoor added to those over time. Basically if parts could be built in a way that an EE can literally reverse engineer by looking at it, it would be hard to add any kind of backdoor. Only thing though I would imagine such a platform would be very power hungry.
Then again, nothing stops the government from adding backdoors to individual transistors, like a separate IC in the same package that then communicates on a common bus at a different voltage. But that would get really complicated as the only thing the backdoor could do is know when the transistor is told to turn on or off. The backdoors would need to communicate with each other to get an overall picture of what's going on. Could purposely use transistors from different manufacturers throughout a single cpu to make it harder for any backdoors to talk to each other.