An ETH Zurich team have done a triple core lockstep version for cubesats: https://www.theregister.com/2023/10/05/riscv_microcontroller...
Gaisler is also current one of the biggest players there IIRC. I've used them for stuff in the past.
An ETH Zurich team have done a triple core lockstep version for cubesats: https://www.theregister.com/2023/10/05/riscv_microcontroller...