Here's some 25-year-old Finder arcana for you:

If you hold the command key, you can drag and drop files, apps, applets etc into Finder's toolbar for one click access

@stroughtonsmith I thought I knew every Finder trick by this point, and I had no idea this existed. I'm amazed.

It does look like there's a non-AppleScript/Automator way to run shortcuts, though:
- link to a shortcut using its URL scheme, shortcuts://run-shortcut?name=whatever
- save the link as a webloc/inetloc file
- then drag that file to the toolbar the way you did.

You can even pass parameters to the shortcut that way.

@csilverman @stroughtonsmith Ah, URL handlers. Driving trucks through the wires in the wall since System 7.5.