Sup Nathan, I edited the title for a suggestion.
Minecrafr has a data command that lets modify containers and entities's inventory: merge, append, prepend and replace.
merge: replaces the inventory to the template
append: add the item to the last slot
preppend: add the item to the first slot
replace: ?

It would be great to also have a CheckData to check for item x with y parameters, including CMD, NBT, tag and name in z slot and k ammount.