We could extend all dropdown-pages controls with buttons to Edit the selected page or create a new page to be added to the selection:

This would implement some of the similar behavior that was added to Customize Object Selector: https://github.com/xwp/wp-customize-object-selector

See also: https://core.trac.wordpress.org/ticket/38002