nommu is a neat concept, but basically nobody uses it, and I don't see that as likely to change. There's no real use case for using it in production environments. RTOSes are much better suited for use on nommu hardware, and parts that can run "real" Linux are getting cheaper all the time.

If you want a hardware architecture you can easily comprehend - and even build your own implementation of! - that's something which RISC-V handles much better than ARM ever did, nommu or otherwise.