You don't need the full python repl/compiler/interpreter/libraries, you "just" need the python virtual machine. Once there's a C compiler for the platform that should be relatively straightforward, because I sincerely doubt that takes all 128KiB.
I wonder how hard would it be to get a working DCPU-16 backend for GCC or Clang.
GCC already has 4 other 16-bit backends (e.g. pdp11), so it should be achievable.
A Clang backend means a LLVM backend, which I believe is a lot easier than extending GCC, and gets you support for all sorts of languages.