You can't use this approach for conky. These scripts are run before the GUI is loaded and before you log in. Your service is loaded and attempts to execute conky, which promptly exits because there are no available X screens.

This sort of thing should be done via the autorun settings of whatever desktop environment or window manager you are using. Many common desktop environments will run the program describe by any .desktop files in ~/.config/autostart. For example, to run conky create a file called ~/.config/autostart/conky.desktop with the following contents:

[Desktop Entry]
Type=Application
Exec=/usr/bin/conky
X-GNOME-Autostart-enabled=true
NoDisplay=false
Hidden=false
Name[en_US]=conky
Comment[en_US]=
X-GNOME-Autostart-Delay=0

You can't use this approach for conky. These scripts are run before the GUI is loaded and before you log in. Your service is loaded and attempts to execute conky, which promptly exits because there are no available X screens.

This sort of thing should be done via the autorun settings of whatever desktop environment or window manager you are using. Many common desktop environments will run the program described by any .desktop files in ~/.config/autostart. For example, to run conky create a file called ~/.config/autostart/conky.desktop with the following contents:

[Desktop Entry]
Type=Application
Exec=/usr/bin/conky
X-GNOME-Autostart-enabled=true
NoDisplay=false
Hidden=false
Name[en_US]=conky
Comment[en_US]=
X-GNOME-Autostart-Delay=0