I built a very simple circuit to listen to 5V pin of HDMI and I hid RPi and the circuit under the desk of a colleague after work and turned off video output of RPi.
Colleague's laptop -HDMI> RPi -HDMI> external display.
when the colleague comes to work and turn on the laptop, my RPi turned on its video output and external display showed the website I made for the occasion.
I built a very simple circuit to listen to 5V pin of HDMI and I hid RPi and the circuit under the desk of a colleague after work and turned off video output of RPi. Colleague's laptop -HDMI> RPi -HDMI> external display. when the colleague comes to work and turn on the laptop, my RPi turned on its video output and external display showed the website I made for the occasion.