Risc-V is a free instruction set for CPUs. Find more info here.
Clifford Wolf did implement MCU class Risc-V core and integrated it into the SoC icoSoC which does run on the icoBoard. So you can use the icoBoard as Risc-V MCU developer kit.
Currently Contiki OS is available as operating system running on iocSoC on the icoBoard.
Others did port NuttX to the Risc-V, but it was not yet tested on icoBoard.
We hope in the future to have available microPython on the icoSoC.