Today I started trying to control a bunch of LEDs through the built-in Arduino controller. For this I followed this guide: https://udoo.org/docs-bolt/Arduino_Leonardo_compatible(ATmega32U4)/Getting_Started_with_Arduino_Leonardo.html
It's super simple: just download the files, install with the two scripts (one fixes some permissions issue). Then it directly works. One of the pins(13) has a built in LED. One of the example sketches can directly control it. This gives me hope lol.
configuring the neopixels seems easy enough, following this guide and translating to the pin out from the guide above: https://learn.adafruit.com/adafruit-neopixel-uberguide
It seems that I should be able to power around 28 LEDs quite comfortably (not too bright) with the 5V power supply of the board itself, so without a separate power supply, which is great. There are som examples in the library that comes with the Neopixels Arduino library and they immediately work!