What problem does this address?

The navigation block currently supports menu items (page, custom, tag, category, cpt) links, and it allows Social Links, Spacer, and Search blocks. These:

With these blocks, you can create a range of navigation patterns if you combine it with other blocks:

However a range of patterns are still out of reach, such as these:

What is your proposed solution?

Allowing a range of additional blocks inside the navigation block would enable these and more patterns. For example enabling site logo or site title, combined with Navigation space-between, would enable the patterns discussed here: #31610 (comment)

For that reason, we should expand the range of allowed blocks in the top level navigation menu:

• Site Logo (perhaps also image, see Add image to Navigation block #30101)
• Paragraph (as suggested in Navigation block: can't unlink items #18866 (comment))
• Site Title
• Site Tagline

As each of these are added, it will also help hone and improve the horizontal and vertical alignment tools, as well as, potentially, each of the blocks allowed in.