Make the shopping the simplest for you and your family. Use the phone app to always add groceries when you think of it. Then use the watch app to check groceries in the store. No need to carry or juggling a Grocery list in the store. Use the watch that is not occupying one of your hands.
The lists have excellent space efficiency giving a good overview of large lists. If a grocery item text cannot fit on fitbit screen the text will scroll to allow you to ready it anyway.