Related to #19256.

There should be a way to load a specific context for a template (a "post" for single , a "category" for category, a series of posts for archive, etc) in preview mode. This could also be tied to the “browsing” mode as navigating by clicking would also effectively load a specific context (a page, post, category, etc) automatically.

In more sophisticated templates, like a complex magazine layout on the home, with multiple article queries, this should be both intuitive and flexible.

One consideration could be to always load some content by default (like latest post) and ensuring the display clearly indicates it's for preview purposes.