Microsoft SharePoint Online Site Directory Listings
The Microsoft Online Admin Center (MOAC) provides Company Admins/IT Gens (IT Generalists) with the ability to manage their Online Users & Services. In particular these Admins have the ability to create and manage their SharePoint Online websites through a SharePoint Site Directory List, found in the Service Settings --> SharePoint Online Tab:
Currently any Company Admin/IT Gen that can access the Microsoft Online Admin Center (MOAC) can view this site directory and attempt to access the sites, even if they don't have permissions to access the site. If the user doesn't have access, they will be taken to the SharePoint Request Access webpage, where the user can request access from the SharePoint Site Collection owner, as seen below:
Future Microsoft Online Milestones will restrict this list of SharePoint Online Websites to only those in which the IT Gen/Admin have permissions to access.