Yeah, M-Series aren't made for things like smartphones. They're primarily IoT and Automotive focused, and the M0 and M0+ variants are positioned as 8 and 16-bit

Yeah, M-Series aren't made for things like smartphones. They're primarily IoT and Automotive focused, and the M0 and M0+ variants are positioned as 8 and 16-bit microcontroller replacements. Vendors typically don't add DDR SDRAM controllers to their implementations of M-Series cores, so memory is limited to SDR, which would be too small and too slow for a smartphone. Processor speed is also too slow - generally in the 10s to few hundreds of MHz range, with ~300MHz being the fastest for the relatively high-performance Cortex M7.