There are really two steps here:

1. Get the project to a point where chibicc-uxn.exe (running in Windows/Linux/etc) can compile the codebase to cc.rom, and this cc.rom can compile something FizzBuzz-sized.
2. Get the project to a point where even this cc.rom (running in Uxn) can compile the whole codebase, and reproduce itself.

The biggest limitation is uxn's limited memory. Right now, chibicc-uxn allocates more than 64kB of memory to compile any non-trivial program. So the former sounds difficult enough, and the latter feels a bit like a pipe dream.

Here's the work that needs to be done:

• Implement more standard library functions, like calloc and strtol and sprintf. A few of these are in lib/ already.
• Remove stuff we don't support from the chibicc source code (like long).
• Right now we rely on an external preprocessor. But such a thing doesn't exist in Uxn-land, so it's probably a bit more meaningful if we at least implement #include and #define. It could be a separate program.
• Severely reduce the memory usage somehow, or find a clever way to manage memory.