https://github.com/MicrosoftEdge/MSEdge
> We will evolve the Microsoft Edge app architecture, enabling distribution to all supported versions of Windows including Windows 7 and Windows 8, as well as Windows 10. We will also bring Microsoft Edge to other desktop platforms, such as macOS.
Mainstream support for Win7 ended in 2015, for Win8.1 in January 2018. The only mainstream supported versions of Windows are various Windows 10 editions.
(1) https://support.microsoft.com/en-us/help/14085/microsoft-bus...
https://www.theverge.com/2018/12/6/18128648/microsoft-edge-c...
That may be so, but is there anyone outside of MS who believes in UWP? Not even stalwart MS exclusive devs seem to do so.
The fact is that if they want to support Windows 7, 8.1 and macOS it naturally cannot be kept as UWP app, as their infrastructure requires Windows 10 features.