They send me the binaries for OS/2 for every release till 2016
Apparently modern C++ and Qt run there without issues
On a related note, "Showstopper!: The Breakneck Race to Create Windows NT and the Next Generation at Microsoft" is a surprisingly entertaining story, and reads more like a novel than a documentary/memoir.
As a result of a feud between the two companies over how to position OS/2 relative to Microsoft's new Windows 3.1 operating environment, the two companies severed the relationship in 1992 and OS/2 development fell to IBM exclusively.
https://en.m.wikipedia.org/wiki/Windows_NT :
Windows 3.0 was eventually so successful that Microsoft decided to change the primary application programming interface for the still unreleased NT OS/2 (as it was then known) from an extended OS/2 API to an extended Windows API. This decision caused tension between Microsoft and IBM and the collaboration ultimately fell apart.
https://en.wikipedia.org/wiki/OS/2
tl;dr A graphical OS developed by IBM that succeeded DOS and competed with Windows. Notably, it featured pre-emptive multitasking before Windows did. It was not a success in the home market but was reasonably successful in big business, especially finance, for a short amount of time.