After you create an app in Visual Studio you can build it by running msbuild. You don't need an additional build script.

But how do I run the built app?? msrun? msbuild run?? dotnet can "dotnet run" but msbuild??

This is Windows dev: while command line is available, everything has been thought for the GUI. Use Visual Studio, it will provide a much better experience. There's a button for what you want to do on VS (green arrow, at the top, the hint text is "run" I think).

For a packaged app, this may be relevant:

https://docs.microsoft.com/en-us/windows/msix/desktop/deskto...

There is a way to launch packaged apps from the command line once you have registered them:

https://docs.microsoft.com/en-us/windows/uwp/xbox-apps/autom...

Everything with packaged apps is harder, so I try to avoid it.

Thank you!