I don’t have any concrete above but I do know you can put a PI on the RPi using GPIO. That should give you an event. I’m sure that there is some sort of screen saver software you can send an event to cancel the screensaver.
Quoting an rpi doc page:
Try to install xsceensaver
sudo apt-get install xscreensaver
Once this has been installed, you can find the screensaver application under the Preferences option on the main desktop menu. This provides many options for setting up the screensaver, or disabling it completely.
Of course you need to plug in the mouse and keyboard to do it ^^
I can suggest to also enable ssh access so you can manage some aspect from another client.
If the monitor is also CEC compatible you can make some script to turn it on and off at certain time (maybe at night you want to turn it off).
edit: I forgot to link the doc: https://www.raspberrypi.org/documentation/configuration/screensaver.md
What I had in mind was to use a openhab rule to turn off the screensaver (when an event is triggered)… I dont know if it´s possible yet, but I assume it somehow should be.
Well, “fantastic” readme… Nothing mentioned about the options… Just how to install it 