What would need to be changed to create a new standard stream?

Hopefully this question isn't too abstract, it touches on a bunch of software throughout the stack. We all know about /dev/stdin, /dev/stdout, and /dev/stderr. What if I wanted to create a new standard stream, /dev/stdjson? What software would need to support that? I'm assuming that I don't *need* to pass a file descriptor to /dev/stdjson to every program, that they can open that stream on an as-needed basis. So where could you add a new standard stream? Would it need to be a kernal module, a part of the shell?