NOT RECOMMENDED: Das Keyboard "Q"
I have a Das Keyboard 5Q keyboard running on my Mac. (The current version of my keyboard is the "5QS".) Each key is backlit. Individual keys can be set to any color or unlit. Das Keyboard offers a collection of "applets" that you can run, or you can write your own in Javascript. The applets can use the key backlighting as an information display. There are applets to show you the weather, stock market values, if a server is down, etc.
I use two applets. One is the Weather USA applet. The Weather USA applet uses four keys to show you the weather forecast for today and the next three days, where Yellow=sun, Purple=overcast, Blue=rain, and Red=Thunderstorms. The other applet I use is the CPU Usage applet, where a row of 10 keys progressively illuminates like a horizontal bar meter to show CPU usage.
Das Keyboard has Q software that supports Linux. IMPORTANT: Some Q keyboards do not support Linux, so pay attention. Although Das Keyboard was well-established as a company, the Q product line started as a Kickstarter "investment." The original 5Q was very late and the software is still awful. To use it, they force you to authenticate with their servers over the internet, which I detest. They claim that their Linux software supports Ubuntu and some versions mention Mint. Either way, people have complained about the Linux software, and I do not think that they invest much in Linux software testing, so you take your chances.
I have never tried connecting the 5Q keyboard to a Linux system myself. My Linux systems are all virtual machines or VPSs. A long time ago, I connected the Das Keyboard 4Q to a Windows virtual machine to update the firmware, but it took a special configuration with a second keyboard. At some point, the keyboard could be updated directly from macOS, and I am not eager to repeat the experience just to see the Linux software, so sorry.
Das Keyboard had a chance to own this market by releasing their software as open source, and they should have never required an active online connection with authentication just to use their software. Enthusiasm for the 5Q was high back then and the number of applets and market would have exploded. For whatever reason, the software remains closed and starved of resources, the world moved on, and Das Keyboard missed their golden opportunity. They still come out with new models, but now they are "niche". Sad, really.
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The only reason I am posting this is because @CrazedNerd mentioned keyboards specifically for Linux. This is an example of a quality keyboard with specialized Linux software to program the backlighting. Repeating: NOT recommended, due to poor software and an authentication requirement.