Portable Getch for Elixir?

I’ve had difficulty to find a simple & portable getch implementation for Elixir. The use case is for CLI scripts, where the user is prompted for a single-character keypress, without needing the return key.

I’ve looked at ex_ncurses, rustler, System.cmd, Ports, etc. This is the best I’ve come up with so far:

#!/usr/bin/env elixir

ruby_cmd = ~S"""
  ruby -e '
    require "io/console"
    @output = IO.new(4)
    @output.sync = true
    char = STDIN.getch
    @output.write(char)
  '
"""

IO.write("Press a key > ")
port = Port.open({:spawn, ruby_cmd}, [:binary, :nouse_stdio]) 
receive do
  {^port, {:data, result}} -> IO.puts("\nChar: #{result}")
end

This works on my Linux dev machine, but depends on Ruby. Does anyone know of a portable getch implementation? Maybe with Rustler and precompiled Rust binaries, or ???