[joezydeco]

"And these devices have graphics displays but they lack GPUs? What device could that be?"

I've deployed Qt HMI projects on Cortex-M3/M4 devices like the NXP LPC1788/4088, and GPU-less A9 cores like the Renesas RZ/A1L. I've even done one on a wacky Chinese MIPS core.

They all use a raster framebuffer + LCD controller. Works just fine for a hell of a lot of things. I have yet to do a HMI project in Qt Quick, nor do I plan to in the future.