I'm currently using pouches and bags as containers and it can be a little difficult remembering what pouch is for what without opening them up.
My dream inventory containers:
Camp supplies: in game ?
Alchemy bag: in game ?
Key ring: In game ?
Gem bag: pretty please
Scroll case: with a cherry on top
Potion rack: kind of in game already, just needs an auto function
Book case: item exists (hollowed out book) needs auto function
Wares container: desperately need a container for automatically storing items marked as wares.
I'm sure there are more I've missed.
Being able to rename containers would also be amazing as well for some.extra storage options.