Does the Banner Topic accomplish what you’re looking for?
The banner shows for all users — but once a logged in user dismisses it then it’s gone forever; anon users can dismiss it (but the dismissed state is only saved locally on their device).
Additionally, you can target anon users using CSS (we add the class .anon to the HTML tag).
There are also some CSS classes to target either the topic-list pages (body.navigation-topics) or category pages (body.navigation-categories).