The tablet itself runs https://www.fully-kiosk.com/ to display a web dashboard. Fully Kiosk has good Home Assistant integration, including screen on / off controls. I also have a bunch of Sonoff battry operated zigbee motion sensors scattered around the place. Then Home Assistant does what it was meant to do - act as a glue layer between various systems, firing screen control commands to Fully Kiosk as a result of select motion sensors triggering.