Deciding state of a projector

I have an Optoma UHD55 and after hours of searching, it apparently doesn’t work with Telnet, PJLink, etc. To automate my theater startup and shutdown, I need to know the state of it, so what’s some creative ways to do that? Energy monitor plug? Light sensor? Looking for advice from you experienced folks…

I presume state as it reliably on / off using hdmi cec control

Light sensor is a very interesting idea.
Only worry for me us random bulb blowing. If LED or Laser i’d expect all is ok and if it not work user will report