In 90 minutes, I have made a desktop with my preferred color scheme that features two applications (file explorer and notepad) and a sidebar of icons which looks strangely similar to the "Shelter" interface in PENUMBRA:BLACK PLAGUE, which I was drawing on for inspiration. This application compiles to an 800K binary that runs directly off of a 4 megabyte "hard disk" on a PCMCIA card (I paid 50 cents for it) which is plugged into the side of the 486 100MHZ laptop I recently painted orange. It runs in 640x480 VESA 256 color mode at 60+ fps, realtime updating of screen region happening underneath the notepad or file explorer. I am only learning now how to add an off-screen context in Photon Application Builder so it is flicker-free.
This application could be just as easily running on a small dedicated AMD processor or using an LCD monochrome device without much hassle implementing it.
QNX is absolutely the perfect platform for Vault OS. Everything about it is perfect. It has all the programming frills of something like VB-DOS for rapid development on x86 devices with all the power of 32 bit protected mode C++. The sheer amount of drivers and source code for x86 machines is intimidating. Anything you could possibly want to do with it, there is likely a bit of source code that will show you how to approach the problem. It's almost like Borland C++ Builder for "PIP-Boy."