Most Discovery boards have an Arduino compatible header with at least an SPI and I2C pins, and some of the timer pins broken out. Now if your GPIO needs is more specialized than that, then none of the dev boards (from ST or otherwise) could ever sati...

these boards have many useless devices onboardNot quite sure what would qualify as "useless devices onboard" in a Discovery board

This is the most frustrating about the STSAFE series, there are no real reference manual. You have to use the STSAFE driver from ST, and if you are having issue, its almost impossible to troubleshoot.

I'm sure SPI or I2C pins are broken out on those headers, so yes, you can certainly add a basic SPI/I2C based LCD display

Go with the STM32 Discovery Board as most come with external peripherals such as LCD, storage flash, sensors, wireless communication, etc.https://www.st.com/en/evaluation-tools/stm32-discovery-kits.html#productsThis comes with WiFi, Bluetooth, extern...