I just stumbled over this project:

https://libre-soc.org/

MMIX is created by Prof. Knuth purely for expressing his algorithms. Back then C++ and Java were the latest, hottest sh… (and would soon be outdated themselves). Prof. Knuth didn’t like C++ and general programming language fashion. So he invented MMIX. It was never meant to be implemented in real HW.

I don’t know whst’s wrong with the other CPU architectures you listed. I especially wonder why Sparc wasn’t used more.

I don’t know of an industry company who builds truely libre hardware. Only half-libre if you are willing to call it so.

Which region are you willing to work in?

Windows -> GNU/Linux

KDE/Gnome -> JWM

TV -> Reading books

Twitter -> Fediverse

Coke/Cola -> Tea/infusion

Amazon -> Local bookshop