On the redesigned "Following" page, you can pin users to the top of that list through the "manage" button that appears on the right column. That column is hidden on mobile devices with no alternative way to manage those pins.
One easy solution I'd imagine is to add the pin option to the meatball menu on user profiles. Although ideally, there should probably be a way to manage pins without leaving the following view.
I'd add that this also helps if you follow a lot of pages. When I found out I had access to it, I went to pin someone and had to scroll through the 300 people who'd posted since they last posted.