You could add a direct link in the Hamburger menu using Custom hamburger menu links, the link is:
/u/user-map?period=location
However, please note that the user directory takes a very short time to load as it’s only loading one page. Even if it visits that route first and then transfers, you will find the majority of the time is spent loading the large number of users in one go for the map, as it’s much much harder to ‘page’ for a map view.