Favorites in Opus can point to files; the UI is just geared around adding folders since that's what favorites are designed for.
Make a button or hotkey which runs this command:
Favorites ADD=nameonly PATH {filepath$}
You can then select a file and click that button to add the file to your favorites list.
Selecting the favorite will take you to the folder it is in and highlight the file.
You can also add files and folders to toolbars, menus and sub-menus by simply dragging them to the toolbar while in Customize mode. Clicking those will launch the file, but you can also edit the buttons and add the Go command before the file path to make it do the same thing as a favorite would.