The Site usage page in SharePoint Online (SPO) is one of the pages that has received more updates for the last few yers. In the las wave of improvements added to that page we can find the following new features:
New and improved Unique Visitors and Site Visits charts which shows information about those metrics for the last 7, 30 and 90 days.
New Popular Platforms chart where we can see the devices and platforms used by our users to access the site (Desktop, Mobile Web, Mobile App, Tablet, Other Devices).
Two lists wit the Most unique viewers and Most viewed documents for the last 7 days. Finally, at the botton of the Site usage page we can also find the documents that have been shared from the site.