at the time....
//greybeard recollection warning//
IBM was looking at OS/2 not only as a standalone OS, but to be the user exec for their other systems; AIX, MVS, and AS/400. Those systems we all know were (and continue to be) dominated by the classic green-screen. Having passed on an opportunity to buy Apple, IBM was looking to push their three dominate systems down-scale into small business and home user environments. NT and OS/2 were to be the gateway drugs in that effort. The MSFT interface was for home consumers while a similar but more 'focused' Workplace Shell was for business. Either UI would have been able to run on the same hosting OS and on multiple hardware architectures.
Even then there was early work in flight to condense the multi-chip implementation of the RS/6000 chipset into what became the Moto 68x influenced Power architecture. The roadmaps that eventually pulled in the then independent MVS and AS/400 CPU implementations into Power were largely in place in the mid-1990s.
IBM stumbled twice at that point. It was the unfortunate delay in getting viable PPC/Power cpus into the market (PPC 601 was a disaster for everyone but Apple) which in turn was a key factor in losing the desktop UI and developer base to Wintel.
OS/2 (Workplace Shell really) running on PPC 604e was pretty damned fast but the economies of scale for systems production just wasn't there. AFAIK, Workplace Shell never made it onto Power.
IBM tried to pick up the pieces with OS/2 partnerships on both Sun and Xerox. The Xerox hookup in particular was interesting as it was bringing the Most Excellent Xerox XDE and ViewPoint/GlobalView environments to a user exec that could in theory run on the three classic IBM hardware platforms plus the evolving 16/32 bit Intel platforms. Alas, the best that partnership could deliver was a Xerox Mesa emulator card (ISA FTW!!) that would run under Solaris/Sparc or Intel-OS/2.