Review on Keywish Expansion Board: Raspberry Pi 2B/3B/3B+/4/Zero Compatible Sensor Board, 5V 3A Support, 8-Channel ADC Reading with MCU by Rick Vidaurri

This board is great for experimenting with Raspberry Pi GPIO. This board shares the GPIO pins, making it easy to connect analog sensors to STM32 to read the analog signal and perform an ADC to send to the Raspberry Pi. 8 channels can be used on the board, which means that several analogue signals can be fed in at the same time. Great for prototyping or experimentation. No documentation was included, but it can be found by searching the board on Google. The online instructions will help you set up the board on your Raspberry Pi and enable I2C communication to communicate with the board.