OS for the cloud is exactly what it is. I see AWS, Azure and GCP as OEMs for cloud, just like Samsung, Oppo, Motorla, etc are OEMs for smartphones. Android was the open source abstraction across these devices. K8s is the open source abstraction across clouds.
The meaning of "app" on top of these two operating system abstractions is entirely different and the comparison probably doesn't extend beyond this. From a computing stack standpoint though, it makes sense.
