This required stretching the terminology so much that now, by your definition, any software that interfaces with anything else in a restricted/controlled manner is OS-like because that's just like interfacing with hardware.
I get why they chose the word - this is marketing, they want to make it appear foundational, as a cornerstone of every interaction you do. But I don't think it's a fair comparison - the OS is the lowest level layer of any computer (barring firmware and the likes) and it manages nearly everything that happens between the user and the computer, the OS is mandatory to use the computer and it runs basically everything. This is just an app - a very sophisticated app that manages other things, but still just a layer over existing systems. If they get to call this an OS, then maybe Microsoft could call the bundle of their Office suite and all the enterprise software an OS too, I'm sure there's enough functionality, depth, features and app-driven oversight over data for it to qualify.
Or "COSIOS": CloudflareOS Is Not an OS.
Sent from my Gmail OS