It is tempting to treat apps as something special, but the opposite is true. To a screen, an app is content like any other.
An app goes into a playlist alongside your images and videos. It takes its turn in the rotation, holds the screen for its slot, and hands over to the next item. It follows the same schedule rules and plays on the screens you choose. The audience sees one smooth sequence, the app blending in no differently from the image before it or the video after.
This is the quiet strength of treating an app as content. You do not learn a separate system to use one. Everything you already know about playlists and scheduling applies, and an app takes its place among the rest.