Open Geany Template with Shortcut
Solution 1:
Geany does not provide a command line interface to open new files bases on a template. Directly creating a shortcut that launches Geany that way therefore may not be possible
You could work around with the Template system of the standard Gnome desktop. Link the template of Geany you want to be easily accessible into your "~/Templates" directory. Create that directory if it does not exist.
Then you can create a new document based on the template using the "Templates" entry in the right-click menu (clicking on an empty part of the folder). You can also summon that right-click menu with the shortcut key Ctrl+F10.
Thus, Ctrl+F10, d will allow you to select the template. A new document, which is a copy of the template, is placed in your folder. You can then rename it and launch it in Geany.