photOS is a lightweight Linux-based operating system for a DIY photoframe. The software syncs photos with a dav server so new images can be easily added. In my current setup I use Nextcloud as server, but any dav server should work. With Nextcloud I can use the Android app to directly upload images from my mobile phone. In addition, I can share the photo folder with other family members, so they can add photos as well. Even from a distance during pandemies...
Main focus are the Raspberry Pi boards (especially Raspberry Pi Zero W, as the performance is sufficient). But as photoOS is based on the great work of thingOS by ccrisan, which builds on top of Buildroot, other boards can be easily supported. Just create a ticket for not supported boards.
The hardware requirements are minimal and the system is easy to setup, as only a Raspberry Pi and an old monitor is needed. But you can spend a lot of time in the woodwork :-)
The installation, configuration and update of photOS is documented in the wiki.
For additional information have a look at the FAQ and the growing wiki pages.
Don't hesitate to add questions as issues labled question if soemthing is unclear.