Fun read. I'm pretty sure there were ways to run SCO SysV binaries unmodified on Linux (and I think FreeBSD and others), back in the day. Maybe something to do with ibcs2?
OpenBSD removed it as they did not feel they could properly maintain the system.
FreeBSD keeps a little of it around, mainly to run linux binaries.
NetBSD it looks like they kept the whole buffet.
iBCS = Intel Binary Compatibility Standard. iBCS2 = iBCS v2.
Not the same thing or even related.
But there was a native MS Word for Xenix. I installed that on several production systems. It offers easier file interchange with modern word processors, and it was a bit easier to use. Less powerful than WP 7, but also less arcane.
I'd love to see that running again.