Welcome, you amazing community of The Amazing Game, especially you Wube Software lads!
So I haven't been following the amazing game for a year or so; only downloading latest update every few months but not the forum, so some suggestions are already or to some extent implemented, at least in some mod.
TL;DR
custom grouping tags to be used in inventory sorting and some quick inventory visual displayWhat?
I suggest possible sorting mechanic that is to add some sorting grouping tag (customized per player).The game would likely assign a default tag, but can be overriden individually by every player, local to each save of a global dictionary, to define what item goes under each tag.
Let me exemplify it: we know inserters and belts go hand in hand almost all of the time when building or supplying. So I as a player can adjust the way chests (and my chacracter's inventory by extension) are sorted by (instead of the sorting way player's inventory is sorted by). One might interject, but inserters and belts are already in the logistics tab, and sorted together already, but say for some reason I want combinators to be together with pumps, or steam engines with burner inserters, or artillery with turrets. That's a custom grouping.
So say I'd like to see the logistic stuff in the chest first, then industry ones (like machines and modules), and lastly military stuff. As a multiplayer thing, the content of each container won't be unsynced; it could have in-game an alphabetical order, but player sees its content in different order.
Speaking of the adjustment menu, I'd expect it to look like the GUI of upgrade planner, but with headlines of tags (default ones ofc), underneath which are the items that go under that tag, that have slots that expand as more items are defined under each tag.