Adafruit’s QT Py ESP32 Pico board is the smallest ESP32 board I’ve found:
See: Adafruit QT Py ESP32 Pico.
It achieves this by packing components onto both sides of the board, and still manages to include a NeoPixel RGB LED and two I2C ports, one on the edge connector and one on a STEMMA QT connector. For more details about using it with uLisp see:
Its performance is the same as other ESP32 boards. Use the ESP version of uLisp Release 4.4c.