Software

Openframe

https://openframe.io/
It’s in alpha and has been abandoned since 2020
The original creators moved on to develop a closed source project, that tries to achieve the same thing, which is a shame.
There is a critical issue that prevents the project working without a rewrite of some of the code

Dynaframe

https://github.com/Geektoolkit/Dynaframe3
Newer versions are proprietary
It was built with Avalonia .net framework

tyler-tee’s Digital-Photo-Frame

https://github.com/tyler-tee/Digital-Photo-Frame
Serie of scripts to display pictures from google photos
Here is a tutorial

Other software

Most tutorials out there for a a digital photo frame use an image visualizer like feh and a serie of scripts to download pictures form sources like google images.

Hardware

Samsung The Frame

https://www.samsung.com/us/televisions-home-theater/tvs/the-frame/55-class-the-frame-qled-4k-ls03d-qn55ls03dafxza/
Literally just a TV with a matte finish

Amazon Echo Show

https://www.amazon.com/dp/B0CDWWS127?th=1
Literally just a TV with a matte finish x2

Aura frames

https://auraframes.com/
I’m not completely sure about the underlying tech
They provide an app where you can upload pictures
It lacks onboard storage, it needs WIFI to work for cloud storage (concerning for such a simple product)

Other cheaper options

Most cheap options out there are Android tablests with a carousel app preinstalled.