Apr 07 2021
Microsoft is currently rolling out a SharePoint app bar that features global navigation on all modern SharePoint sites (for targeted release tenants).
The first tab in app bar is a Global navigation. Global navigation is the only app bar tab that can be customized. Read all you need to know about global navigation at: Enable and Customize Global navigation
Prerequisite for enabling global navigation
How to enable the global navigation?
How to customize the global navigation?
Different options to choose navigation source
How to edit the global navigation?