@thatbrickster @yomiel >low-power >performant >accessible >affordable.
You can pick 2 at most.

You'd probably be best off finding the best Aarch64 SoC you can find, porting free software to it and then spamming them onto the biggest PCB you can get PCB companies to make, while spamming RAM slots and I/O ports and GPIOs and enjoy the 5 years of PCB design and software porting.