>Especially the part to do with compositing together multiple spatial apps living together in the same shared space and even interacting with each other (eg: one app can emit a lighting effect that will shade the other's rendering).
This is the killer app, but where do you see that capability?
Oh, right. That eg is more of an ie, though. Almost nothing Apple or other VisionOS developers have showcased has taken advantage of this capability. Not even, "If I throw one virtual app at another virtual app, they bounce off each other." I've seen some experiments, but nothing in production. Everyone seems to be terrified of making spatial apps that take advantage of the fact that they "live" in a "space" that we can move our bodies through.
This is the killer app, but where do you see that capability?