There’s still lots left to do, but the core functionality — GPIO ... pinout, so you just need to look it up, and hook up MOSI to MOSI and so on. As of now, it only uses one of the ESP32 ...

It also has all of the I/O you would expect something based on an ESP32 to have, such as I2S stereo DAC, an I2S microphone input, I2C GPIO extenders and, of course, a built-in MicroSD card reader.