I’d be curious to know what sort of values you assign to something operating as a PKM? It seems to have a visual component to it that isn’t something I would at first associate with the genre as necessary for something to be included within it. To put where I’m coming from in perspective, my “PKM” (if one would be so inclined to jargonise it) has no software requirements at all, and consists entirely of a formalised network of metadata found in plain-text files, essentially all thrown into the same folder together by the thousands. It’s simple enough that it could operate on a box of index cards, but just tuned enough to keep millions of words from getting lost. There is nothing at all visual about it, but that’s how I organise almost all of my information.
When I think of ideal software for this, Scrivener does in fact comes to mind, and as it stands. Here is a recent discussion, which has some links that branch off into other discussions—one of which in fact goes over Scapple vs Scrivener and how well the former is suited toward a role in this area.
So with that all in mind as background, what do you find missing in what it provides?