I can start a command in a new Gnome Terminal as follows:
nohup gnome-terminal --window-with-profile=Background --command ls >/dev/null 2>&1&
(Based on https://askubuntu.com/a/46630/7146 and https://stackoverflow.com/a/10708326/236081)
However, I want the new terminal window to start minimised in the Launcher. How can I do that?