STM32MP157 is a microprocessor, not a Microcontroller :-)
Still cool though. The STMP157-BASE-SOM-EXT: https://www.olimex.com/Products/SOM/STMP1/STMP157-BASE-SOM-EXT/ looks especially useful as a Rasp-Pi like system. The obvious intent is for the EE to pick-and-choose which parts they want for the board (ex: Ethernet, or CAN or whatever) and specifically design their own.
But on the other hand: a SOM + Expansion board is only 30 EUR + 30 EUR == 60 EUR total, likely cheaper than Rasp. Pi 5 and with fully open-source KiCAD designs to boot.
The 2MP MIPI CSI camera on the evaluation board is very nifty and makes this a more complete solution for a lot of robotics applications IMO.