I can't seem to find what the cross inventory slot is for (near food), how is it special. There is a page on TG1 wiki which doesn't have it https://github.com/pWn3d1337/Techguns/wiki/Techguns-Inventory-Tab, there's no such page on the TG2 wiki. I can't find any explanation anywhere too.

This slot is not yet in use. The plan is for auto healing items, like a stim pack for example.