hi, you could just use an array for the items. make the items spawn after every let's say randomly between 10 and 20 seconds. when you want to display the items in an inventory, you could just make use of the array some how, either in a menu with the dynamic menu or make your own menu if you would like.

Practice involves an array of spawnable items. In your loop, after a certain amount of time elapses, select a random element from said array and spawn. As for inventory, I'd personally use a dictionary formatted as item_name:amount specific to each entity. Let me know if code would  be beneficial