The light color picker shows the x and ‘y’ value (why is the latter quoted?), but it would make sense to also show the RGB value as that is what you can use in a script using rgb_color. I often use the color picker to find nice colors and then want to make presets based on that color.
I know you can also set xy_color, but this custom card only shows previews of the color when you use rgb_color 
Would make my day if this is added 
Image of the current situation:
