Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

You can make pull requests with your own folder of pixel art and follow the same format

./[your name here]/[title].gif

32x32 grid magnified to 64px works well for animated emoji that you can have in chat platforms as tiny reactions or messages.

LibreSprite is a free and open source program you can use for creating and animating pixel art:

https://libresprite.github.io/