Tanaka Jimha tells us all about MSIX, the package format for installing Windows apps, including how to package your existing code with Visual Studio and how to deploy and distribute your app, via the web, the Microsoft Store, or an Enterprise distribution network.
A file with the .msix extension is a Windows application installer and an updated alternative to .exe, .msi, and .appx packages. MSIX preserves the functionality of your existing app packages and/or install files, in addition to enabling new, modern UI features and deployment options for Win32, WPF, and Windows Forms apps.
Here are some links to learn more: