I am currently making a racing game with customization, and I want the equipped body parts to save. The only thing I found about saving things (except datastore) are the SaveInstance/Boolean/Number/String functions, which are deprecated.
You might be able to have an IntValue in the things you want to save and save that number. Then when someone joins the game again you cycle through the saved numbers as well as the Items a player can get with a for loop and give them the matches.