OPENSTEP Enterprise 4.1
ToDo - Elaborate on this topic, further, based on Discord discussion, from a while ago. Need to investigate compatible Windows versions, build numbers, introduction date, and other info, at some point, too...
OPENSTEP Enterprise 4.1 is a port of the OpenStep APIs, Adobe's Display PostScript engine, the NeXT/GNU Objective-C toolchain, and graphical application development tools, to Windows NT (3.51/4.0, x86), Solaris (SPARC), and HP-UX (HP-PA).
The Windows port is based on a modified version of CygWin, Congruent ToolBuster, and newly-developed adaptation layer code, by NeXT, and has additional functionality, to support interoperability with OLE, and Visual BASIC/COM.
The Solaris, and HP-UX ports use HP, and GNU components, and NeXT-developed code, to provide an OS abstraction, in place of Mach.