I love this sort of interface. I want to have a use for it, but I haven't thought of a use case yet.
So handy to just shoot a text instead of opening an app and navigating to the right list.
Not sure about the grocery list use case. You have already input your items and they are still visible in your message conversation with Nina, making the response back from Nina redundant in nature.
I tend to email myself article URLs from my phone to my laptop, so I think I will try using Nina for that.