The good RISC-V designs are not free though and the free ones are not good. MCUs are not a category of computer to draw lessons from for the broader market.
In the MCU market the compute core is already an off-the-shelf drop-in component. Just look at the RP2350: in addition to its traditional ARM cores they also last-minute dropped in two RISC-V cores because it was so trivial to do - and you can select which set is active via a boot-time firmware flag. I very much doubt we'll see that kind of flexibility with high-end client compute, but with the switch to separate compute chiplets we're not far off already!