TinyPICO
TinyPICO is the world's smallest, fully-featured ESP32 development board in a package smaller than your thumb!
TOMU
Tomu is a programmable computer that fits inside a USB port. It is user-programmable, has two buttons and two LEDs.
Teensy 4.1
Teensy 4.1 features the fastest micocontroller and an expanded set of powerful peripherals in a 2.4 by 0.7 inch form factor.

Teensy 4.1 features the fastest micocontroller and an expanded set of powerful peripherals in a 2.4 by 0.7 inch form factor.

An open source, RISC-V development platform with wireless connectivity/

This adaptor board connects Teensy 3.2 - Teensy 4.1 to thousands of LEDs using the OctoWS2811 Library.