This is an extension to hide the top panel on GDM login and lock screen.
With a multi-user desktop system, you may not want average users getting their paws all over Quick Settings in the top panel at login. My workstation is acting as a desktop, a kiosk and a network server (over WiFi) so the last thing I need is Jamesy disabling my network connection at the login screen whenever I leave the keyboard on the couch while I go get a coffee...
Jamesy is a sheepdog and I know him, very well.
To make this extension available to all users on the system, install in the /usr/share/gnome-shell/extensions directory. Note that newly-installed machine-wide extensions are disabled by default.
$ wget https://github.com/surfinky/gnome-login-hide-panel/archive/main.zip -O ./gnome-login-hide-panel-main.zip
$ unzip ./gnome-login-hide-panel-main.zip
$ sudo cp -r ./gnome-login-hide-panel-main /usr/share/gnome-shell/extensions/gnome-login-hide-panel@inchsurf.com
Now, restart your Gnome session to complete the installation.
You will see the extension listed under the "Built-in" section of Gnome Extensions list. Duly enable the extension and adjust preferences as per your liking. It is recommended that you restart your GDM session so that changes to preferences take full effect.
$ gnome-extensions enable gnome-login-hide-panel@inchsurf.com
$ gnome-extensions prefs gnome-login-hide-panel@inchsurf.com
Note authorization is required to apply changes for the login screen.