When a group (folder) is selected in DEVONthink’s sidebar, Hook say’s “no linkable item”. All documents and groups (including tags) in DEVONthink have an “Item Link” that is discoverable via OSA script. So, Hook should be configurable to find the URL of a group.
Sample, which works when the item selected is a group in the sidebar.
tell application id "DNtp" set theSelection to the current group set theURL to the reference URL of theSelection set the clipboard to theURL end tell