[PeCaN]

You can find QNX 6.5 and suitable license keys by digging around on the web a bit. 6.5 is probably the last version suitable for use as a desktop OS—I believe 6.6 is where they started to remove the ability to self-host, and the GUI was completely removed by QNX 7. (It's a shame, because IMO the Photon GUI is really clever.)

Unfortunately QNX 6.5 is pretty old and not too well-supported (QNX is fully POSIX-compliant so you can sometimes get things working on it without too much trouble however) but it's damn fantastic to play around with in a VM. It's actually so fun.