This has been around for a long time but most people don’t know about it:

Dragging and dropping files from the finder into an file selector window (ie. Open File in most programs) will navigate to that file and select it. As others mentioned this works in terminal as well to give you a path, but actually this generally works in any text box (unless it specifically handles paths being drag ‘n dropped). This also works with multiple files / multi file selection, and in the case of inserting the path as text, they are space delimited and auto quoted (convenient for shell use).

Edit: This icon can include the one at the top of a finder window (the window title). That’s actually interactable and can be dragged and dropped for the directory itself.