How do you envision the system working? Were you just thinking that turning the knob would rotate through a pre-built palette of colors, which would be shown on the knob's RGB first then transferred to the final device or something where you could control the mix of RGB by pushing the encoder's button to switch from controlling R, G, and B until you get the desired color on the indicator LED then maybe a double push to transfer it to the final device? I don't think either would be too difficult, but given the differing methods for specifying a color to the various RGB devices, I'm not sure how accurate the preview color will be on the knob's LED.