Most of those would be meaningless, or require enough decisionmaking that the program between them cannot reasonably be called a driver. What kind of driver translates between audio and window system objects?

In any case, you only need 2N for translating both ways between file: and whatever: to get the same experience Unix does, and wherever that makes sense it is usually provided.

The win is of course that each of those protocols can be strongly typed and provide exactly all the operations that make sense for that protocol. Basically, think of all the things IOCTL does and give them their own names.