How to display full-screen image based on sensor data?

I want to have a message screen based on the readings of a couple sensors. I can handle the sensors - but I’m looking for help on how to display a full-screen image and then change it based on those sensors. There’s only about 3-4 status scenarios, so I’m going to make an image for each. I want them displayed on basically a stand-alone screen. I can wallmount a monitor and put a Pi or chromecast or something on it, but then how do I display an image and control which one?
I thought about a dashboard with a picture card on it, but I don’t see a way to full-screen that.

I think? Wallpanel allows you to automate changes of the background, it definitely allows full screen?