Windows Mobile devices were able to replace small form factor desktop devices like mini PC, Mac mini or Chromebox. This ability was named Continuum. It requires responsible apps. While this is a standard for web apps, it is not for desktop apps. Investments to make desktop app responsible is much higher compared to web app because XAML and Windows API were not designed to responsible scenarios. In addition, Surface Duo will not come with Windows 10X, but Android instead. It makes Continuum ability technically impossible. For these reasons, future version of Feed Viewer for will drop Continuum support.
Current version (150.1), which supports all versions of Windows 10 since 10240 build, will not be updated with new features, but it keeps Continuum support. Future versions (150.2) will no longer support Windows Mobile, Continuum or Windows 10 version 1809 or below. However, it will be ready to obtain support for dual screen devices when they come.