And there lies the common misconception of the UWP. It's an application model that can target multiple devices of developers choosing. Why would you assume I or any reasonably thinking person would want such a complex application as Sonar on a phone?!
That's just unreasonable.
Now I can see a new DAW built with the mobile user in mind (small screen 5"-11") from Cakewalk.
See Image-Line's FL Mobile 3 and Allihoopa's Figure as examples of a true UWP apps for mobile and desktop: They're both well done.
I want to see a UWP desktop version of Sonar.