I’m using Debian 11 appVM.
protonvpn-cli needs access to the gnone keyring, which is why I use the autostart option, autorun runs the file after login when the desktop is ready.
I have got I working with rc.local, but you need to check when the dbus file is created, it was just easier to use autorun.
You just need to make a .desktop file in /home/user/.config/autorun, and this file can be used to execute your connect script.