How would the client know to update if the user is viewing the page/cell with the old data and it updates underneath the covers?
Polling interval seems super reasonable! You could also add a button to manually refetch the queries using the refetch function available to cells: Queries - Apollo GraphQL Docs. I think you can just destructure it out of the props, like
export const Success = ({ refetch }) => ...
And as @thedavid said, subscriptions would be super interesting as well.