Super+, or Super+F11 to fullscreen a window
This is a bit more involved and would need work in cosmic-comp. Ideally, we'd have an OSD similar to apps with the shortcut to un-fullscreen the app.
@maria-komarova would appreciate your thoughts on the shortcut. I like Super+F11 because it matches the common F11 shortcut to fullscreen. Downside it it can be hard to get to on some laptops.
Super + , is already busy for the magnifier. Super + F11 sounds good because it is a common one (F11). I can't yet think of a good alternative although I agree that it is could be hard to get to on some laptops and keyboards.
Super + ENTER could be a good alternative. Ideally it would be configurable.
For me Super + F makes much more sense and easily accessable, but again I am more used to hyprland, and as long as it's configurable nobody will mind any other.