That’s just a String. It’s not an Item. It has no .state. It’s just a sequence of characters.
You need to access the actual Group Item. If all you have is the name of the Item you need to pull that Item from the ItemRegistry. See Design Pattern: Associated Items.
With the details provided, it might be a better solution to use the semantic model potentially as you can get the Equipment that one Item belongs to and from there get the associated Online Item from the Equipment.
In the other rules languages it’s much easier to get at an Item when all you have is the Item name. But in none of them can you append two Strings and instantly have an Item.