Why not asking a PS4 emulator with stereoscopic 3D and internal 4k upscaler for textures?
May not be necessary.
According to programing genius Carl who is not cynical about this sort of thing.
How CPU intensive is it compared to DolphinVR?
I'm not sure. Probably less CPU intensive because PPSSPP runs on mobile. But PPSSPP normally uses a single core for both CPU and graphics.
Any possibility of using this to play PSP games stereoscopically, say on a display that supports SBS stereoscopy?
It's not implemented yet, but there's no reason why not.