Alt text: meme with the 'Always has been' format Linux, MacOS, OpenBSD and ChromeOS logos on top of the Earth The first astronaut says 'Wait, it's all Unix?' A Windows logo, on top of the second astronaut. The second astronaut says 'Always has been' and points a gun to the first astronaut.
everything is a file, except when it's not.
Everything is represented by a file, doesn't mean you can open it with a text editor.
More like file descriptor. File path is like address system, but it's not how you get all file descriptors. For example: sockets (there is bash's fake /dev/{tcp,udp}), epoll, timer, event, inotify.
In UNIX systems event systems have a list of filedescriptors with a callback for each. You could have your event loop an epoll fd itself and nest it in another.