You want freedom hardware? Start with RISC-V, and to verify - you'd have to build your own CPU and other chips, I suppose lol.
Yes, someone did manage to create their own RISC-V CPU at home, but how powerful is it? How much power do you actually need to?
I'd say that, for general computer usage - I'd need it to play at least 720p videos at 30fps, with like CPU still having some room. Preferably 1080p@60fps..
But perhaps you want to roll your shit anyways - because it's fun, you can feel important, and you do learn.. If it can play Anarch or alternatives - it might be good enough for a lot of things, just not playing videos of decent quality, which is quite important to some people like me, because - I consider movies to be quite important.