This is something that honestly deserves so much more. Back in the original scope of NT OS/2 it was going to be a C parallel of OS/2 2.00 Cruiser that had the promise of running on one of those new fangled microkernels, and those trendy RISC workstations. The 486 / Pentium were considered like the 68040/68060 to be the peak of CISC processors and from there on it was going to be a RISC world, the only question was to be which one?
Many of the Motorola customers who couldn’t afford to make their own (SUN with the SPARC), or license a school project (SGi with MIPS) were expected to use the 88000 processors that were expected to eclipse the 68040. There was an Apple initiative, and even a NeXT RISC Workstation built among many others. Only with the launch of the 88010 it was discovered performance was nowhere near expected and it’d take significant work to fix.
Back on the i386 side, Microsoft had been working with Intel on their upcoming RISC, the NTen aka i860. And just like the 88000 it too had performance issues, which resulted in Microsoft retargeting the MIPS.
Things changed along the way, and not only was the primary CPU platform dumped, but Windows 3.0 became such an incredible seller that OS/2 Cruiser was dumped from NT OS/2, and it became Windows NT. NT had been promised with the ability to run OS/2, MS-DOS, and POSIX applications, with an emphasis on Win16 and the new extended Win32 applications. However MS-DOS was super limited, POSIX was just enough to run vi & tar, Win16 was incredibly slow as it ran through WOW (Windows on Windows), and OS/2 had been kneecapped to the 16bit 1.x support as it was primarily a vehicle for running Microsoft SQL Server 1.0/4.0 . Another consequence of this is that OS/2 was command line only. In the back of deployment guides, and resource kits there was always an inference to a Presentation Manager subsystem for NT, although I’d never seen one in the wild.
Until I got a hold of a bunch of Microsoft Select CD-ROM’s that mostly were multilingual service packs of Office and Windows 98 / NT 3.51 & NT 4.0 But burred in there was a copy of Presentation Manager for NT 3.51!

First off it’s a text based install. It feels like October 1991 all over again. It installs a parallel OS/2 directory with presentation manager support.

Once it is installed it’ll setup program icons from the Windows NT side. Presentation manager runs in a separate window from the GDI. This is akin to how OS/2 would run Windows in a ‘full screen’ session. So oddly enough both support each other’s 16bit applications full screen, while reserving the desktop for 32bit applications. IBM would later introduce dual mode video drivers capable of rending Windows and OS/2 applications at the same time. Clearly Microsoft would never do this.

Launching the control panel reveals that it’s OS/2 version 1.3. No big surprise there. You can return to the Windows NT desktop either via the Windows NT icon in the bottom right, or via a Control+Alt+Delete.

The DeScribe 3 beta installs pretty smoothly into the subsystem. However running Describe is a different story:

It hangs trying to open or do anything. Even the ‘help about’ is too much. Such a pitty.
The readme warns against trying to copy the file manager from OS/2 although it does tell you what files to copy in manually. Naturally there is no ‘console’ for Presentation Manager, rather that is handled on the Windows desktop.
No doubt there had to be some big customer that demanded a way out for their investment in Presentation Manager on Windows NT. Otherwise this would have been built in. And it’s only 5 diskettes so it’s not a space issue. I suspect since it was on a Select CD, it really was not meant for wide scale distribution.
Last time I tried, Excel 3, and Word 1 had issues running on Windows NT, as the loader tried to intercept them as Win16. Things didn’t go so well. Or maybe it’s my memory. I went ahead and installed Excel 2.2 for OS/2

Despite it being text mode, it has Presentation Manager hooks, and needs PM Shell to be running. It’s a simple setup program, but yes, it’s text mode.

One nice thing about Describe & Excel is that they can see the program groups on the NT side, and create icons over there. However NT has no ability to read OS/2 resources so the icons are all incorrect.

And yes, Excel for OS/2 runs on Windows NT! Back then Excel was super expensive, this is before the big Office OEM bundles that took over the industry. So I could totally see preserving this massive investment in Excel.
Despite having 80286 emulation in the earlier versions of NT, and 80486 emulation in Windows NT 4.0 (Yes DooM runs on the MIPS!) the OS/2 subsystem was never available on the RISC platforms. I suspect had Windows 3.0 not been a big seller it may have. Then again without the big ‘rabbit out of a hat’ like DOS Extenders, Windows would have died on the vine. Who knows, maybe NT OS/2 is a thing in a parallel universe.