I would take an other approach. The problem has two sides:
- Collecting the URL's
- Launching the URL's
For the collection I would set up three different KBM macros, one for each application you want to support. All 3 of them would use the same shortcut and only be active for the given application. As an example the macro when fired on OmniFocus would copy the item link using the Menu "Edit -> Copy Item link", when fired on Obsidian it would have to do a right click on the selected item and then use the menu item "Copy Obsidian URL", etc. KBM is very capable of executing these actions.
For the launching, in theory it would be possible to have the above capture scripts also create a keyboard macro so the URL's could be selected using a palette, but as others said not very practical. I suggest you take a look at the article Pick List which presents a list to the user to select from. A possible approach could be that the capture scripts, write (append) the collected URL's to a file, either one big for all your URL's or one for each application you want to support. Your launch script would read the file and present it in the pick list after which you can launch the required application.