Understanding inventory system

[Item] is item definition, a logical object that is unique to your game. Usually, [Item] has [Id] and [Count]. Player's items may be stored as a part of a player's profile in [PlayerPrefs]. Trader's items may be constant ("hard-coded") or generated at runtime based on player's progress.

[ItemParams] is item description. It may contain uniques information for your game like type, weight, price, attributes and other. A full list of all item parameters is some kind of item database and is usually constant (stored in game resources).

[ItemCollection] is a scriptable object stored in Redources that contains a list of [ItemParams]. You can use it if you want, or just make your own implementation.

Ok, now we have separate separate [Item] and [ItemParams] classes. Knowing an item's ID we can find its' params at any time.

While [Item] and [ItemParams] are LOGICAL objects, now we want to get some VISUAL things like equip items on characters or implement an inventory system.

[SpriteCollection] is a list of all sprites available in Hero Editor. It's also a scriptable object. [ItemParams] class contains [SpriteId] property. Using it you can find [ItemSprite] in [SpriteCollection].

Nice, now we have following workflow. Knowing [Item.Id] we can find [ItemParams]. Knowng [ItemParams.SpriteId] we can find [ItemSprite] in [SpriteCollection]. Then we can can equip it on a character.

[IconCollection] is a list of all icons available in Hero Editor. Icons are usually used in inventory systems. Please note, that sprites from [SpriteCollection] may be associated with multiple icons. For example, an armor sprite (atlas) has helmet, vest, bracers and leggings icons. [ItemParams] class contains [IconId] property. Using it you can find [ItemIcon] in [IconCollection].

Finally, our workflow is

1. Define all [ItemParams] in [ItemCollection] scriptable object that is stored in Resources. You can use any external sources like Google Sheets, for example.
2. Define player's profile and add a new property List<Item> Items, it's a list of items that a player owns.
3. Knowing [Item.Id] find [ItemParams] in [ItemCollection]
4. Knowing [ItemParams.SpriteId] find [ItemSprite] in [SpriteCollection]
5. Knowing [ItemParams.IconId] find [ItemIcon] in [IconCollection]