I would suggest a sane nesting. Single column (per side, major list anyway).
Super-categories of items (expandable), like "Food"
o Sub-categories if items (expandable), like "Milk"
o o Items, like "(containers of) Cow's Milk".
The trouble being that the obvious hierarchy, the Stockpile list, is quite awful in parts. Glob stuff, for one. Under the Meats, there's optional subdivision of source-creature then the various subtypes of (cookable) meats. Or would you prefer the other way round? Bags could be furniture subsetted, but they are containers in non-built circumstances (and, whichever, do you subdivide bags by material, or by cloth-class then precise cloth, adding layers). What if you want to accumulate (for review, at least) items made of Steel, do you need to dig into weapons, armour, furniture, toys.. etc, all separately, or could you switch to Material-property sorting? Before you have optional value/cost sorting.
This problem applies to multi-columned versions too (the first organisational category in multilayered drop-down collapsability could be the headers) and I don't propose this as a visualisation problem suitable for this thread, just raising it as something hovering in the background of the issue.
I'd also like to see the way this screen behaves with respect to resizing. Already I'm unsure about the ellipsis use in the various Vordak examples (it shows that we're at a limit of easy display) yet this is an image that is already depicting a screen far wider than I can see properly on most of my desktop displays and all my other ones (despite the ultra-widescreen ratio and fairly good resolution on this tablet, I can't seem to scale it well enough). I know the "5 plump helmet..." duplication is copypasting, but there'd be some definite cases where that truncatuon would matter IRL.