Let’s look at food in 3.x: only quality state present. I think it would be cool if some sort of quantity percentage would be in 4.x. And I think there should be a possibility to combine two items resulting in sum of the quantities and the medium in quality.
As well with clothing and guns. If the dirtiness state reaches a high number, later use will take the quality.
A vest + another vest = 2 vests . To combine 2 vests you should need a “device” and some materials for it
And you get a repaired vest + some raw materials from the second vest.
From combining 2 guns you get parts that are in plus from the combining process.In my opinion.