I have setup with 10 Raspberry Pi kiosks that run Chromium in full screen, and that works great most of the time.
To make sure all monitors are working ok they have cronjob that sends screenshots via email twice per day.
But that is a lot of emails to go trough each day, and most of the time all of them work ok, so it is really tedious going trough 10 screenshots twice daily.
First idea is to simply display images (two groups of ten images) from last two runs that are sent to central server. I can setup so that screenshots are saved into custom folders, and then some simple html could show it. I have no idea how to do html and display part.
Other more advanced idea would be to have some image recognition app that would "look" at photos and know if chrome is running and showing something or if it is an empty desktop. Because we have always same colour header on the screen that would work simply by looking at one area and checking if it is green (chromium running) or beige (wallpaper from desktop).
If you have any ideas or implementation tips please share them.