If you missed Ignite 2020 you would of missed a very exciting annoucement of the SharePoint App Bar coming to SharePoint Online at the end of this year. The app bar will bring global navigation across all of your sites and will use the navigation that is setup from your SharePoint home site.

SharePoint App Bar brings global navigation across your SharePoint tenant.

The app bar will not only feature a link back to your home site but links to your recent and followed sites, news from your sites and recommended sites. I would highly reccomend checking out the video that goes more in depth about this feature at this link: https://techcommunity.microsoft.com/t5/video-hub/architecting-your-intelligent-intranet-with-sharepoint-global/m-p/1681225