HP-UX is still alive until 2025 apparently. I used on my workstation for a while (an HP Visualize C3000) in the 90s -- it was my first 64-bit workstation. It's not great.
Interesting. Haven't used it for a while. I miss that OS. Last used it some years ago, so things have moved on since then. For the time, I found it good, though. And HP had pretty good quality in those days - in both hardware and software (the stuff I used, anyway).
Also, I only used it on HP business servers - the PA-RISC series, not on their workstations. Don't know, but there could be some differences in the HP-UX versions between the servers and workstations, the latter which, IIRC, were based on the acquisition of Apollo (but don't know much about that).