Creating a dynamic menu I'd like to make a Drupal 8 menu dynamic so it can i.e. point to the latest node of the articles or news or hide another from the menu if it doesn't have an entry at all.

How can I achieve this?
You can't really have dynamic menus that point to different things. You can write a deriver and so on, but that will be persisted and not updated until you tell it to. You can trigger the necessary updates also without a full cache clear, see how MenuLinkContent does it, but it's still persisted.

Another approach would be to not make the route/output dynamic and not the menu. Point to a custom controller, and there you either dynamically display the latest node (can easily be done with a view, for example) or you redirect to the latest content, to avoid duplicate content.