Is there a keyboard shortcut to switch the focus between monitors in GNOME on Ubuntu 20.04 LTS? I do not want to have to move the cursor between monitors, or Alt-Tab to the window on the other monitor.
Alternatively, I would be fine with a solution that assigns the first workspace to the secondary monitor, so that I can simply switch to the first workspace in order to switch to the secondary monitor.
There is a related issue tracked here, about having a separate workspace per monitor.
As per a comment in the above link, you can enable workspaces for all monitors, but switching the workspace on one monitor causes it to switch on all of them (i.e. workspaces are not independent as per this feature request).
You can consult this link for keyboard shortcuts for moving between workspaces, namely
Super+Page Up
orCtrl+Alt+Up
,Super+Page Down
orCtrl+Alt+Down
.Unfortunately no, it apparently does not work this way in Gnome. In Gnome, you switch applications and/or windows, and the focused monitor will be where the window happens to be. This switching is done using Alt+Tab or using the application overview, that happens on the primary monitor.
There is little or no control on which monitor a newly started application will be opened. There are shortcut keys, though, to move a focussed window to another monitors: Super+Shift+.