Arduino is an open-source electronics platform based on easy-to-use hardware and software. It's intended for anyone making interactive projects.
An Arduino Uno is an excellent option to drive your SMARS. The SMARS case was specifically designed for the Arduino UNO (or clone). Official Arduinos are more expensive than Raspberry Pi Zero WH's and are only 8 bit but there is a wide range of open source code available, and they have plenty of IO pins.