This is the Orchestra (https://github.com/WildGums/Orchestra) shell with Syncfusion Ribbon.
Included themes are Syncfusion FluentLight and FluentDark.
To use other theme, include theme dll and set a default theme name in the application App.xaml file (see example).
To enable switching between light and dark theme include both dlls in the application (for ex. MaterialLight/MaterialDark).
Only new SfSkinManager themes should be used.
NOTE: When running in Debug mode, application will crash with NullReferenceException when switching themes or theme colors.
Syncfusion controls work for 30 days with a trial license. After that they need a license. There is a free Community license, which can be obtained from the Visual Studio marketplace (https://marketplace.visualstudio.com/items?itemName=SyncfusionInc.SyncfusionCommunityLicense)