There are 2 repositories under logitech-rgb topic.
Add RGB LED illumination to your games and applications made with Unity, Unreal Engine, C++, and .NET. Spectral adds RGB LED illumination on devices on all supported brands (e.g. Logitech, Corsair) instead of only the devices of a specific brand.
This is a C# program using Logitech LED SDK. It can set your device's LED color and it can cycle smoothly through two colors instead of three provided in the LGS. For example: Blue to magenta, magenta to red, red to magenta, magenta to blue. Repeat.
A simple Windows application that renders audio data on your Logitech RGB keyboard
Manual profile selection and creation utility for the Logitech G810 mechanical keyboard.