My aim is to separate my working space from any other spaces while using the same computer and the same OS. When I start the operating system (Ubuntu 20.04), my desktop environment (Gnome) starts automatically. Then, when I press Ctrl-Alt-F3 to switch to another virtual space, log in as a different user and type sudo gdm3 or sudo systemctl start gdm3, then nothing apparently happens. If I enter sudo systemctl isolate graphical then another Gnome session starts in this virtual space, but when I try to log in, the keyboard stops working altogether, or the system simply halts until a cold reboot. Also, startx -- :2 or startx gdm3 -- :2 gives no desired results as a graphical interface seems to load and then immediately unload.
Can someone please clarify how exactly can one start another Gnome session in a different virtual space while using the same desktop environment in another virtual space (say, the Ctrl-Alt-F2 one)? I know this must be possible, but how exactly is not quite clear at this point.