Unrelated: Would this be suitable for a CV system eg in robotics? Eg do the realtime stuff on the Cortex-M, and run a linux + OpenCV/OpenVINO etc on the Cortex-A?
The appeal of STM32MP1 is you can put DDR momery with the chip on a 4 layer board. ST even provides the layout.
The outer balls take up space and so block the traces from inner balls. By strategically removing some of the outer balls, you create channels that can be used for routing taxes from the inner balls.
Nevertheless its 64-bit core is optimized for low-power, so it also has low performance.
If the applications intended to run under Linux are more demanding, one may need at least some SoC with Cortex-A55 cores (e.g. from NXP), if not one with medium-size cores, like the RK3588 (with quadruple Cortex-A76 + GPU + NPU + some Cortex-M) or one of the overpriced SoCs from Mediatek, Qualcomm or NVIDIA (these latter 3 have worse price/performance than Intel/AMD CPUs).
Unless a price under $100 is a condition, the easiest way to make a CV system for robotics is by using one of the very small computers that are available with Intel N100 CPUs (there are models much smaller than a NUC, either at a Pico-ITX size or even smaller, while prices are under $200).