Simpler alternative in which I am also really interested is to yank the path of a certain bookmark. Then I just could use the regular copy command and insert the desired path as the copy destination. There is a list-bookmarks function in which one can see the file/directory paths, but I don't know how to grab them.
In buffer *Bookmark List*, from C-x r l (command list-bookmarks, aka bookmark-bmenu-list):
With the cursor on the bookmark you're interested in, use
C-h RET(orC-h C-RET).This shows info about the bookmark in buffer
*Help*. For a bookmarked file or directory this includes an entryDirectory:, which shows the directory. Just copy that text.