The design patterns catalog looks amazing! I will definitely going to read that stuff. And thanks for asking around :)
Never heard about a "Factory Method" or some of the other things on there. In the space game i think I'm using 3 different methods at the same time :P I have made some inventory systems before and the upgrades are in a way similar. adding scriptable objects to a list and instantiating UI slots who take in the information from these scriptables.
After the jam let me know if your mac version of the game(s) is online by the way :)