@DariBer
Another solution is to create a script to run the command “xset dpms force off” to turn off the monitor and “xset dpms force on” to turn it on.
Use this video as an example to create something similar.

https://youtu.be/Tw0mG4YtsZk

@DariBer
Yes, that’s what I imagined.
To be as simple as possible.

Sorry for my english, I’m using a translator.

@DariBer
The simplest way to do this is to use a presence sensor that lights up lamps, and connect the sensor to the monitor’s power.
When someone approaches it turns on, and turns off the monitor when no one is around.
It can be done in other ways, but it will be much more complex.