Logitech Litra support
The Litra Beam and Litra Glow devices (link) are USB devices[1] that use the HID++ protocol to communicate with the device they're connected to.
Some preliminary work is underway in the kernel make those devices supported through the hid-logitech-hidpp.c
kernel driver and standard kernel LED API.
Ideally, any work to support those devices would be using the standard kernel interfaces if possible, meaning that any devices with a similar user-space interface could also be supported.
[1]: The Litra Beam also supports configuration through Bluetooth, which I believe would still be using the HID++ protocol and could be supported through the same kernel driver.