One of the simplest ways to set up a pictures’ screensaver from a NAS is to use Kodi. Your photo location on your NAS does need to be shared in some way for this work, either by setting up an SMB or NFS share, but for most NAS owners this will likely be already the case. Once this is done, setting up Kodi is fairly trivial and can be done with any client that supports it, including an Android TV, Raspberry Pi, Android tablet and even an iPad if you are prepared to sideload.
Once you have Kodi up and running, navigate to:
Settings > Interface > Screensaver > Screensaver Mode
Clicking “Add More” will offer a range of screensavers available for download, but the one we are after is the “Picture Slideshow Screensaver”
Once this is installed, you can add a network location to the screensaver in the same way you would add a location to the Kodi library. You can set the timeout and choose a range of transition effects, including Ken Burns.
Using Kodi as a pictures screensaver works well, but there are a couple of caveats. Firstly, there is no way to set the Kodi screensaver as the default in Android, meaning that Kodi has to be open in order for the screensaver to trigger.
Secondly, running the screensaver tends to fill up the storage on your Android TV. This doesn’t happen for a while, in fact, it took around 4 years of running the Kodi picture screensaver before I started noticing slow down on my 8 GB Nvidia Shield (available on Amazon) due to full storage. However, it is worth keeping in mind if the storage is limited on your device.