lowend platforms support such as Cortex-M

Hi,
I'm curious about the level of support that modern Linux offers for
low-end platforms that lack MMU components, such as the ARM Cortex-M
family. Specifically, I'm interested in the memory protection
capabilities that Linux provides on these platforms.
While the ARM Cortex-M family offers an MPU (memory protection unit),
I haven't seen many features related to it in the Linux kernel.
Please let me know if I'm mistaken, and any additional information
would be greatly appreciated. Thank you!

Best Regards,
Andy