This Gnome extension changes wallpapers automatically.
Currently it can select a directory locally to load wallpapers from. Other sources of wallpapers are possible but not currently implemented.
This project was started by Jomik, the original Gnome Wallpaper Changer. It was continued by Ssk101 in their fork, to update the API to Wallhaven. This was then continued by Ghostkeeper here.
To install, you need to put the source code in a specific folder in the extensions folder of Gnome, and then compile the interface schemas for your computer. Execute the following instructions.
git clone https://github.com/Ghostkeeper/gnome-wallpaper-changer.git ~/.local/share/gnome-shell/extensions/gnome-wallpaper-changer@ghostkeeper.github.com
cd ~/.local/share/gnome-shell/extensions/gnome-wallpaper-changer@ghostkeeper.github.com
glib-compile-schemas ./schemas/
After installation, restart gnome-shell by opening the command prompt with Alt+F2 and the command r.
Looks, by default, for wallpapers in ~/wallpapers and applies them at random.