Though not all “Shields” in the strictly-speaking Arduino sense, a few NeoPixel products are designed to fit directly atop (or below) certain microcontroller boards…
This 5x8 NeoPixel Shield for Arduino fits neatly atop an Arduino Uno or compatible boards (5V logic recommended). Like many of our NeoPixel products, they’re available in RGB and various RGBW pixel types:
By default, the LEDs are powered from the Arduino’s 5V pin. As long as you aren't lighting up all the pixels at full brightness that should be fine. Or power the shield with an external power supply by soldering the included terminal block.
The NeoPixels are controlled on digital pin 6, but with some deft wiring you could change this to any pin.
The NeoPixels are normally controlled from digital pin 6, but pads on the bottom make this reassignable. In particular, the default pin for Feather Huzzah ESP8266 must be moved, try pin #15!
The NeoPixel Featherwing is RGB only; there’s no RGBW version.
The Pimoroni Unicorn Hat is aptly named after a mythical animal — normally we’ll say that NeoPixels don’t work with the Raspberry Pi, but Pimoroni has worked up some magical software that makes this combination possible! It’s an 8x8 RGB matrix that fits neatly atop the Raspberry Pi Model A+, B+ or Pi 2.
Due to the way Unicorn HAT works, you can't use your Pi's analog audio alongside it. If you see odd random colour patterns and flickering make sure analog audio is disabled.