By default, the 'Activities' Overview in GNOME Shell only shows windows from the current workspace.
Is there some way to get it show the all open windows instead?
I'm looking for functionality like that of the Compiz Scale's Spread feature, when used for windows from all workspaces.
Yes it is possible with this Overview all windows extension.
Although it won't work after install, download the schemas folder from its git repo and paste in extension folder.
Path of extension folder:
~/.local/share/gnome-shell/extensions/OverviewAllWindows@amiller27
Overview shortcut will be super+ctrl+tab.