Oh, and being able to transfer the list to the grocery store would be handy too.
Great suggestions! Those are certainly needed features that are not available today. The only thing that Amazon offers are categories for your items (like household items, or frozen), and items are automatically put into those categories.
Hopefully Amazon adds something like this in the future!
Also, I have multiple shopping lists, and because I have set it to be the default skill, I just need to tell Alexa to add <item> (automatically uses the default shopping list) or add <item> to <specific list>