I ran NT4 on a MIPS Magnum R4000 for a while. It worked okay. Could run 16bit x86 Windows/DOS stuff in a weird sort of translation/emulation.
All my Multias (I owned 2-3 over the years) usually ended up with RHEL on them; nobody in the nerd crowd I was in wanted to run Windows on them. They ran so hot that if you sat it horizontal it would keep your coffee cup warm if close enough.
I believe someone got VMS running on one after some hackery with the firmware/BIOS.
I bought an Acer PICA (https://en.wikipedia.org/wiki/Acer_PICA) back in the early 2000s, obsolete by then, just to play with it and Windows NT 4. MIPS still seemed exotic, and there was little free software to use on the platform. I think a port of Office existed, and maybe an early Internet Explorer.
I'm not sure what the point of the ARC ports of NT even were, except Microsoft's attempt to keep its fingers in as many pies as possible and crowd out competitors.
They weren't sure if x86 was going to be competitive in the long run at that point, so they were porting to all the major architectures. I even heard rumors of a SPARC port of NT 3.51 but I've never seen it in the flesh.
Solaris even ported to PPC (specific RS6K boxes) for Solaris 2.5.1; I've got a copy of that ISO image around somewhere but never had the right hardware to run it.
All my Multias (I owned 2-3 over the years) usually ended up with RHEL on them; nobody in the nerd crowd I was in wanted to run Windows on them. They ran so hot that if you sat it horizontal it would keep your coffee cup warm if close enough.
I believe someone got VMS running on one after some hackery with the firmware/BIOS.