Thanks for writing about this in progress work. Having seen repeated concerns about the site editing experience for the last two years, I think this exploration promises a more intuitive navigation of the pieces of the site editor. At the same time, this PR is just a start and part of much wider efforts too: https://github.com/WordPress/gutenberg/issues/36667 & for an even larger picture: https://github.com/WordPress/gutenberg/issues/33094

I wanted to note for anyone reading along and wanting to have a say that I am following this work closely in order to have it as part of an upcoming FSE Outreach Program call for testing: https://make.wordpress.org/test/handbook/full-site-editing-outreach-experiment/ Stay tuned and know lots of feedback will be collected along the way. Of course, you're always welcome to share directly in GitHub too!