And a Javascript capable HTML4 browser, and a decent-looking and performant GUI desktop too.

It's a shame QNX (desktop) died, used to be way more performant and stable compared to Linux or anything else back in the day.

Isn't it still alive in automobile/infodesks?

The embedded version is, yeah. I was referring to their PC version though, which came with a full-fledged DE called Photon microGUI[1]. It was extremely responsive and could multitask without any stuttering, even on ancient hardware like the Pentium II - something wich other operating systems struggled with for a long time. In fact I would say Linux didn't "officially" resolve the issue until they introduced the EEVDF scheduler with kernel 6.6 in 2023.

[1] https://www.qnx.com/developers/docs/6.5.0SP1.update/com.qnx....

The problem is it wasn't really compatible with anything else, at a time when DOS/Windows and Unix-likes were the most common.

It was compatible with the radio and crypto equipment aboard my coast guard ship!