Is there a general way, to add some string to the topic URL, so that the view always navigates to the first / last / “back” post?
This should serve the purpose of being able to create external bookmarks, so that navigation to the preferred position in the topic can be part of the bookmark and trigger automatically when opening the page.
Navigation to the first post is obvious and default with “clean” URL, the question is concerned with the last and back posts.