The ARM version of uLisp now supports two diminuitive ARM-based boards: the Adafruit QT-Py and the Seeduino XIAO:
The boards are both based on ARM M0 SAMD21 processors running at 48MHz, with 256 Kbytes of flash and 32 Kbytes of RAM. They both have USB type C connectors, and identical form factors and pinouts.
For more information see: Adafruit QT-Py and Seeduino XIAO.
You can extend either board with a 128x64 OLED display, I2C RTC, SD Card slot, buzzer, and LiPo battery charger with an expansion board: see Seeeduino XIAO Expansion Board - Works With Adafruit QT Py.