Not a backyard foundry but this guy is attempting to make a "tangible" RISC-V CPU using "As few programmable chips as possible." he wants to use MSI and LSI chips " so things like buffers, flip flops, and so on. "

More details: http://www.halfbakedmaker.org/blog/lmarv1-1

YouTube playlist https://www.youtube.com/playlist?list=PLEeZWGE3PwbansoxKjjMK...

That will take something like 20000 transistors.

0 0 0

Here, I think you dropped a few zeroes.

The Pulp project claims to have designed a RV32E core in 12 kGE. Which, I believe, implies around 48k transistors with CMOS logic.

Note that original MIPS (1983) was done in 25k transistors.