I'm using the curios mods and one mod, which is something similar to the corpse mod, but is purely a datapack, so operates with minecraft commands. It has compatibility with the curios mods: it reads what was in the inventory, stores it in and clears player's inventory upon his death. However, Inventorio slots can't be cleaned with such a command nor they can be read to be stored (as far as I know). I will attach the datapack's lines which I am talking about (you will understand 1000+ times more than I what this code is doing). So my suggestion would be providing some commands for players to operate with inventorio slots, like utility belt slots and additional inventory slots.