I'm that goof who built a desktop-shaped computer with the Milk-V Jupiter RISC-V (RV64GCVB) board last year. The performance was awful compared to recent amd64 setup. The amount of RAM wasn't an issue, but the CPU was way to slow to even run a graphical interface (read XFCE), or compile some simple program in Rust. It's equivalent to those arm926ej-s SBCs ten to fifteen years ago capable of running Linux 2.6, and only suitable for writing code in text.
I'd say give it two more decades, at current pace.
Not really from the ground up. Their XFCE variant is amazingly convenient nowadays.