Feels like we are trying to find rather awkward solutions to what is just a suggestion, in the spirit of the suggestions forum.
People browse on their phones predominantly in portrait mode and the browsers are designed to be used as such.
The situation: On mobile, there is no page navigation at the top of the page when viewing a thread with multiple pages.
The suggestion: Add the page navigation to the top of the page when in mobile view to make it more convenient to navigate around the thread on a mobile device.