Been studying RISC-V for... I think a year now. Bought the booklet outlining the ISA's modules, and have been working down from there.
I have seen various startups and actual products, as well as a bunch of simulators, but I haven't really seen any projects trying to design a RISC-V CPU from the ground up.
Are there any groups doing this? I don't think I'm at a point where I could meaningfully contribute, I'm mostly interested for educating myself.
xiangshan , rocket chip , cva6 , ibex .
All of these are built by non profits (although some of them are more like "trade groups" and not "charities").
xiangshan is probably the most interesting, there is also vroom but it seems inactive for now.