I was going to add that disclaimer, but it's also a step closer and interesting nonetheless.

I'd also recommend Breaking Taps, while he does amazing stuff in a home lab it also has the disclaimer that he's able to get it already has some super interesting but rare stuff. Electron microscope etc.

I thought I saw someone making homemade, low power processors but for the life of me I can't remember who or where.

That's the 6502 one you're talking about though, what about the previous one (granted it still used a bunch of ICs, but not a microcontroller per se)