I don't think you can use Astro to widget shortcut a specific file, just a directory.
no, you can do single files too:
I kinda wanna keep that song there now, haha. One of my favorite FNM songs.
How did you pull up the menu to add the shortcut? When I long press a file, there are no choices for a shortcut. And none of the UI menu options are to create a shortcut.
Just add the Astro widget to the homescreen and navigate to the file you want