This project is no longer actively supported. Feel free to use this as an example but at this point I've moved on to new projects that require most of my time.
This project is an SPFx application customizer built for Modern SharePoint sites / pages. It will place itself in the header placeholder of your site and pull the global navigation from the root site "/" aka "https://{domain}.sharepoint.com/"
It's designed to work for Office 365 primarily but would work on prem 2019. Additionaly it will also generate an output to deploy to Classic Sites.
Most people are running their Office 365 environment in some sort of hybrid of Classic sites and Modern sites. This solution helps to merge the two, creating a consistent navigation across both.
the sp2019 version works for sp2019 and office 365. -this version currently does not build for classic mode
The o365 version only works for o365.