For example, HP-UX was a BSD-based Unix implementation that tried very very hard to pretend it was UNIX System V (R2/R3). "No, no really! I'm not one of that university kids!" But BSD was a far better foundation, vastly better networking etc., so that's what it was underneath.
Unix of the era was billed as a multi-user shared system, but it wasn't always great at that. It desperately lacked much of the quiet robustness and workhorse-ness of the proprietary minicomputer OSs of the day (e.g. VMS, AOS, HP's own MPE). No vendor did more to fill that gap and make multi-workload a workaday reality. HP added a fair-share scheduler (FSS), the first multi-system high availability clustering in Unix (MC/ServiceGuard), and scores of refinements along the way. As a result, in practice HP-UX was admirably hardened, and it ran more users and more concurrent competing jobs per system than any other Unix system could. Often by a wide margin.
In ~1995 HP doubled down on FSS with Process Resource Manager (PRM), which could guarantee various "shares" (weighted priorities) of total machine resources. First commercial Unix ancestor to today's containers. In production ~6 years before BSD jails and Virtuozzo, ~10 years before Solaris Zones, ~18 years before Docker/Linux containers, and ~20 or more years before container were mainstream production vehicles.
Unfortunately for HP, its workstations (the ones OP acquired) weren't nearly as popular with universities and developers as Sun Microsystems', so you tended to find HP-UX in commercial production—larger servers, more workload, but smaller numbers. And thus smaller ability to promote its innovations or be selected because of them.
Hat tip to steely-eyed missile man Xuan Bui and the many unsung engineering stars of HP in the Unix era.