Monome Norns: a Linux-powered open-source sound computer
monome.org
monome.org
Their entire software stack is open-source, and the community contributes an incredible amount. Just take a look at the release notes for the latest norns update [0].
The software itself is also just of a really high quality, especially the balance between accessibility and power. The norns runs lua scripts that interact with a bunch of specific APIs for making sounds, interacting with hardware, or drawing the UI. It's incredibly quick to get started, but folks have made some wild scripts[1]