An interface referred to as "clickthrough" was recently added to make it easy to select any layer of a block with nesting. You to click through each layer, parent block first: Columns → Column → Paragraph.

While this interface is useful as page templates grow in complexity, it also gets in the way if you just want to edit the text of a deeply nested item. In #17088 an idea is outlined for how to keep the behavior of clicking anywhere in text to edit it directly, while still providing an additional way to select the layers of a block.

However there is also potentially room for a more light-weight interface for selecting block layers; a breadcrumb bar could provide a child block first interface:

The bar would sit at the bottom of the screen. It would provide breadcrumbs on the left, and the word-count on the right could absorb the "Document Outline" interface. The keyboard shortcuts for selecting every layer of a block — use arrow keys to dig through layers — would remain in place in addition to the new breadcrumb bar.