I am currently working with FreeRTOS and MKM34 (which is a Cortex M0+MPU) and it would be very useful to have MPU support for cortex m0 as well. Theoretically, the management of the MPU is the same as that of the other processors in the Cortex-M family.
If there is someone else interested we can develop it together.
I’ve not used an M0 with an MPU before (not that I have noticed, anyway, perhaps I was just not looking). If the MPU support code is the same for M0 and M3/4/7 one option might be to create the MPU support in a different file so it can be used with any of those ports. The M0/3/4 ports grew over time, meaning they appear in quite a few places - namely one per supported compiler. We tried to avoid this with the newer ARMv8-M ports (Cortex M23 adn M33) by keeping the common code in common source files.