Adafruit have released an RP2040-based board in the "Itsy Bitsy" form factor, call the Itsy Bitsy RP2040.
The RP2040 is the same CPU as used in the Raspberry Pi Pico.
It can be programmed in C/C++ like an Arduino, or in CircuitPython or MicroPython.
Links#
- Raspberry Pi Pico Python SDK (PDF)
- MicroPython Examples, examples to accompany the "Raspberry Pi Pico Python SDK " book published by Raspberry Pi Trading, which forms part of the technical documentation in support of Raspberry Pi Pico and the MicroPython port to RP2040.