You can make it do a bunch of stuff if you get creative with shortcuts.

My action button silences the media volume (and the phone just in case) and then vibrates the phone to tell me it has done this IF the phone is in a face-down orientation. Otherwise it toggles the flashlight on or off.

I’ve seen people with dozens of actions tied to the button depending on focus mode, orientation, time of day, location, all sorts of stuff.