Is there a "Apple Music App" for Windows10 OR is only the iTunes app available?
The Apple Music app is only available for Macs at this time as your own research has indicated.  I don't think any user here can reasonably speak to any plans Apple has on Apple Music integration for Windows.  If they are an employee, they will be bound by nondisclosure; if they are not an employee, it will only be rumor at this point.  Your best answer for this kind of question will come from Apple's product support team.