Is there a environment variable that one can set to open GUI window in full screen in terminal:
Example: (gnome-terminal is just a particular example)
fullscreen=yes gnome-terminal
fullscreen=yes mullvad-browser
Removed windows
The new gnome terminal (ptyxis) has a preference setting to open new windows in the same size as last closed. The chrome browser does the same.
Those apps are easy to use that way. I cannot answer for a general case with most apps.
There isn’t such an option on standard Gnome as far as i know.
If you want to run all apps fullscreen, the best option is to use a tiling window manager. They will remove all borders and always run the app in the size that you want.
easy way extenssion manager and install
https://extensions.gnome.org/extension/3733/tiling-assistant/
Yes but that is not true full screen mode where the window title etc are removed afaik, it only maximizes the normal window.
yes but easiest way that works on Gnome other way i would go for hyprland or sway and good option Miracle easiest to start WIP still
Does this also work from CLI for any GUI window (for which the .desktop file might not be defined)?
Check out any gui app you want with the executable located in /usr/bin. Starting it from the cli terminal window is usually no different than using the .desktop file. The app usually controls the window used, the DE controls the window size. Some can go full screen without the title & tool bars but some cannot.