I am a developer of Safe Eyes, a screen break reminder to remind the user to blink their eyes and look around.
It runs off a tray icon, and runs in the background.
I tried it in plasma mobile (with Fedora). While the app runs in the background and does remind the user to take breaks at particular interval, since there is no tray icon, there is no easy way to configure the app without invoking command line.
Also there is no simple way (without invoking the command line) to kill the app running in the background.
In Android, certain background apps can be accessed by pulling down the panel from the top. Does something similar exist in Plasma mobile so that the users can interact with background apps?