Do you like to make your own stickers, but hate scrolling through your gallery to find them? uSticker lets you use any image on your phone as a Gboard sticker. Just save the image to your phone and use the uSticker app to import the image into Gboard.
uSticker is free, both as in beer and as in speech. No ads, no telemetry, fully open-source.
Please note that uSticker only works with apps that support Gboard stickers.