Probably best to break this one up into bite-size chunks.... At least based on my understanding of what you have described....So...
Am I right in thinking the Zigbee smart plus has the monitor plugged into it, allowing you to tell the amount of energy the monitor is drawing? Then you want to use this energy reading to determine if the monitor is "turned on" or "turned off"?
The setting of the LED strip colour based on a mode should be easy enough using either a Rule Machine Rule or one of the simpler rule apps... I could provide an example if you need one, when I have some time and more brain-power But rest assured, it is definitely possible, from what you have described.