Today, Microsoft announced that with the release of Visual Studio 15.9, ARM64 development is officially available. The news comes after the firm released a preview SDK back at its Build 2018 developer conference in May.
ARM64 support isn't just for UWP apps, or even Store apps. Any Win32 app can be recompiled with ARM support; of course, if developers want their apps to work in S mode, they'll need to port them to the Microsoft Store. Naturally, compiling a UWP app for ARM64 is easier, as it's just an extra checkbox. Win32 app developers need to add an ARM64 configuration.