I've made a board which is driven by your https://www.olimex.com/Products/IoT/ESP32-S3/ESP32-S3-DevKit-Lipo/open-source-hardware
I'd like to experiment with other MCU's
If you were to replace the ESP32-s3 module in the above board with a M2 slot following the Micromod spec https://www.sparkfun.com/micromod#processor_boards it would be a interesting general purpose dev board format to design around IMHO.
Some more STMxx options in the Micromod format would also be interesting to me.