Safari for Windows was a side effect of the porting work that was happening on the Store to move away from a custom renderer to just using WebKit. And the reason iTunes on Windows was the way it was, and indeed, why iTunes on Mac stayed in this hellacious status for so long, is that it was built on _QuickTime_, which brought most of the Mac Toolbox over to Windows, and then -- eventually -- Carbon.

Objective-C and Cocoa for Windows dates back to the NeXTSTEP/OPENSTEP/Rhapsody days, but yes it’s true. Safari for Windows also utilized this, perhaps to a greater extent, because its UI looked significantly more like its Mac counterpart than iTunes did, to the point that even the text rendering was the same between Windows and OS X.

Yeah OPENSTEP Enterprise (OSE) was a commercial product sold by NeXT and briefly by Apple. Also later versions of WebObjects that ran on Windows provided much of the same tools.