I have a couple of RGB leds in my desktop setup. But currently I'm unable to configure them to work with SimHub. I could write a plugin, but that would mean I need to reimplement everything the arduino leds support.
My suggestion is to change the arduino output to a more abstract Output interface. If such a system was implemented, 3rd parties (like me) could develop plugins which implement the this output interface. One implementation of this output interface would of course be arduino. But others, like WLED, could be implemented. This way, support for many more led outputs could be added by plugins, instead of burdening Whotever even more.