You want to know what pages new users open most often after opening your home page, so you create a new path exploration in Explore that you plan to share with a co-worker. Who can see this new path exploration by default?

Just you; but you can share it with the other users of the property in read-only mode is correct because in Google Analytics 4, explorations created in the Explore workspace are private to their creator by default and are not automatically visible to other property users. However, you can share the exploration so others in the property can view it in read-only mode, while edit access remains limited unless they duplicate the exploration for their own use.