I'm betting I could get an agentic tool to convert the whole thing (XLISP and/or XSCHEME) to modern Rust or Zig in a half a day.

Just the simple interpreter, built in Rust, but yes we can also use the real xlisp, it is pure c, so easy to handle for emscripten, i built in the Benchmark, the original xlisp c in wasm vs the homebrewn interpreter