If you go to anyone's user profile on mobile, you will only see Profile and Calendar in the hamburger menu.
Profile goes to the same page, and Calendar is 404.
I think it's reasonable to expect this menu to hold all of the stuff from the full-width menu. Probably this page needs updating to a more modern Page framework?
This seems a related change:
https://secure.phabricator.com/rP971a272bf679979ef9cc638c3113c98d2fefb186 - Automatically build mobile menus from navigation, and clean up external…
This is the related source code:
What should be available
At list this menu that is desktop-only:
