Hi! If I understand you correctly, you’re saying you’re gonna have Products with 5 different categories right?
If that’s the case, you can create an Option set for Categories and create the different categories you’re using under it. Then under your datatype for products, create a data field for categories and set the type of content to be the option set for category you just created. It will not be a list.
If you meant something else or you don’t understand, pls let me know. Perhaps it’ll be best to have a quick call to explain so I can walk you through the process.