In both OpenStep Enterprise and Yellow Box for Windows, while the UI elements still have some NeXT-isms, it's not terribly out of place, either.
However, this got scrapped sometime when Apple abandoned Rhapsody (which had PowerPC and x86 versions) in favor of Mac OS X (which was originally only available for PowerPC until the Intel switch in 2006, though Apple maintained an x86 version internally during the PowerPC years). During the transition from Rhapsody to Mac OS X, Yellow Box was renamed Cocoa.
The impetus here is that Adobe had initially promised a free, then low-cost license for Display PostScript --- when that was pulled, Apple had to come up with an alternative --- that and the fact that all the major app vendors announced that they weren't willing to do top--to-bottom re-writes using the NeXT frameworks (there was even a rumor that "Yellow Box" was named for the sake of Bill Gates' comment, "Develop for NeXTstep? I'll piss on it.")
So, Apple, led by Mike Paquette and many other talented folks from NeXT created Quartz (née Display PDF) and Carbon and instead of a consistent environment with a single API, we got an assemblage of technologies which had a Calculator app written in Java which took _forever_ to load, a Finder written in Carbon instead of Workplace.app, and icons cluttering the desktop and a Sidebar instead of a Shelf, and a bunch of Carbon apps.
https://forum.winworldpc.com/discussion/11422/openstep-for-w...
It even survived Apple's purchase of NeXT, where the OpenStep API was renamed Yellow Box. There was a port of Yellow Box to Windows:
https://www.betaarchive.com/forum/viewtopic.php?t=29049
In both OpenStep Enterprise and Yellow Box for Windows, while the UI elements still have some NeXT-isms, it's not terribly out of place, either.
However, this got scrapped sometime when Apple abandoned Rhapsody (which had PowerPC and x86 versions) in favor of Mac OS X (which was originally only available for PowerPC until the Intel switch in 2006, though Apple maintained an x86 version internally during the PowerPC years). During the transition from Rhapsody to Mac OS X, Yellow Box was renamed Cocoa.