In wp-admin this is achieved with a text label:

In the current pages list the homepage and posts page appear at the top with icons to denote their purpose:

In the pages data view there is no indication at all about which page serves as the homepage / posts page. Lets come up with a design to achieve this.

There are other situations where such a pattern can be useful – for instance the privacy policy page in core, and the shop / cart / checkout pages are also marked this way – so it could be worth implementing this in a reusable/extendable fashion.