Much more advanced than what I use for this, but I use a small palm size drawing tablet with a magnet back from a Japanese stationery company called KING JIM. It's called the KING JIM BB-12. It was like $15-20, and I find it practical for quick jotting and as for my grocery list I can easily tuck away in any pocket.

I think there's something to be said about not carrying a phone-like device into stores, since the whole "cameras everywhere" situation is feeling more dystopian than it already did. I even carried paper lists to not further contribute to that.