Uses built in commands to change the GDM login screen wallpaper on Ubuntu 24.04, without modifying CSS files or resources directly. I think this may work with Ubuntu 22.04 as well.
These are the sample files for my blog post on Syncing the login wallpaper with the desktop wallpaper on Ubuntu.
To set an image as the login screen wallpaper, use:
sudo ./change.sh ~/Pictures/testwallpaper.jpgTo set the current desktop wallpaper as the login screen wallpaper, use:
sudo ./sync_desktop_wallpaper_to_login.sh https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1929536
https://askubuntu.com/a/1396066/26436