The smallest board offered by Arduino is any of the members of the Nano family. They come with dimensions of only 18 by 45 mm, significantly slimmer than the Raspberry Pi Zero (30 by 65 mm) and ...

According to Arduino, the Nano ESP32 brings plug-and-play IoT deployments to advanced enterprise use cases and hobbyist engineers. The Nano ESP32 18×45-mm development board is available to order today ...