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Without Hreflang markup the en-US and en-GB pages will be treated as duplicate content. You do not want that. In fact, even with hreflang the two may be considered duplicates if there isn't enough differentiated content. Also, be careful with canonicals. You shouldn't specify the en-US page as the canonical URL for the fr page. The fr page is its own page and you should use hreflang to specify other language versions.

Agree with Dirk.  You can use links to show the structure more effectively than the URLs per se.

The feature request link is broken. Has there been any update in 4 years?

I'm having the same issues, revoking access, and reauthorizing does not work.