The app I chose was Lucid Daydream. Download and install the free version (up to 30 minutes of screen saver pics).
Using ES File Explorer I made a Saver folder in the Home storage area.
The pics are prepared (if possible) to fit the TV screen (ie 1920 x 1080). I copied some photos of aurora australis photographed near Tekapo and put them in a new folder.
From the Home screen, I now go to All Apps and locate Lucid Daydream. Click on it to access DayDream settings.
There are 4 settings to choose from. Choose Photo Frame (click on round object at right).
Then click on the icon at far right (alongside the Photo Frame selection). Locate the folder with pics prepared earlier and click to check the box that selects this folder.
This done return to Minix Home ...
.. to make the final settings for screen saving. I choose the minimum time to get the slideshow started.