If you want to explore more OSes that look like this, [Fuschia](https://fuchsia.dev/) is a good one to look at. Rather than having a file be the core primitive, it has an "actor" as the core primitive. And processes send messages to these actors to do anything.

Interestingly, Plan9 started moving in this direction in their later papers. They'd walk through all the many different file operations you'd need to get something accomplished, and then say "but we made a library which does all these things, so you don't need to do it yourself," which kinda defeats the purpose of having everything be a file--and brings you toward the Fuchsia approach.