HP-UX was a pretty good Unix OS. I worked on it for a while at a company years ago. I liked those PA-RISC machines. Pretty rugged and reliable. Did some Unix sysadmin work on those machines for a while. Managing 4 to 5 HP-UX servers, running Informix Dynamic Server, IBM MQ Series and many C, ESQL/C and Informix 4GL apps, later Java servlet and J2EE apps, an early Netscape Java app server (from Kiva, and it even had JavaScript or LiveScript in the server, IIRC - this was all a bit before J2EE first came out, i.e. very early days of Java). All good fun and learning.

HP also had some good Unix tools that were only on HP-UX, AFAIK. Ignite-UX was one of them. It allowed you to set up a configured OS (base OS + kernel parameter customization, patches, etc., init and shell scripts) and then image it onto multiple other machines very easily. Had a real need for such a tool, googled and found it on an HP site. Then installed and used it. The work went like a breeze. I guess there may be tools like that nowadays for Linux and other UNIX-like OSes.

Yes, sad to see this happening to HP. Many years back they had really solid products and tech, and I've read that they were called "the engineers' engineers." I worked in a company that had a joint venture with HP for a while, so saw some of that first-hand.