This looks very interesting, but I don't understand exactly what it's intended to do. Is it intended to be used to replace the way an Org buffer normally looks? Or is it intended to be used in an indirect, cloned buffer to provide an outline-only view aside the regular view (like org-sidebar-tree)?
If the latter, what happens when text is inserted into the outline in the non-cloned buffer? Does it corrupt the display of the visual-outline buffer? (If not, then you may have invented a solution to this problem, which I haven't yet been able to solve for org-sidebar-tree.)
Thanks for sharing this.