I expect you mean NUL (ASCII 0) - but that's typically not a good choice, because POSIX decrees it invalid, along with '/'. But anything else is fair game, sure. Handling every Unicode char might be a pain, but that's the filing system's job, not yours!

Most programming languages manage to get this right. You have a quoting syntax with an escape character that lets you express the quotes, the escape character, and any arbitrary character (as a byte sequence, as a Unicode codepoint in some encoding, etc.) as well. Now you can do everything. Why not do this?

I'm not going to say this won't be a pain if you decide to write out every file name possible, because it will be, inevitably. But you can supply alternative syntaxes by way of more convenient (if limiting) shorthand - Python has its r"""...""" notation, for example, allowing you to express the majority of interesting strings without needing to escape anything.

You might argue that I've just punted the problem on to the text editor and the filing system. You'd be quite right.