Great to see this being more widely/deeply described. It looks very capable, interesting choice with onboard Ethernet switch.
Would be so much fun as a games console, but I guess even at this size programming the GPU bare metal will not be very accessible.
These STM32MP parts are designed for devices with realtime needs and real-world interface requirement, because they combine Application Processors that run Linux (albeit not quite as fast as a cutting-edge phone SoC) with a Cortex-M core made for realtime application use, as well as interface peripherals like CAN. Basically these are supposed to be a bridge between the "embedded" world and the "Linux" world.