The application which allows for external linking must not be handling the link properly.
When I launch a UR link like
ur://D:/Temp/test.urd?item=1026,1006,1000&pos=5954
in the Windows Run dialog, UR is launched to open the DB and navigate to that item and position within it.
This also works when entering the link into a browser such as Edge (after a prompt about a web site wanting to open an application), Windows Explorer, etc.
This is standard Windows functionality that is being leveraged and will work in any Windows application that properly calls ShellExecute API or similar.
https://stackoverflow.com/a/38205984/156738