If there was a coffeescript REPL (I guess there is?) you could probably modify it to send the code you write direct to Espruino - a bit like in the implementation of https://www.npmjs.org/package/espruino-cli?
Espruino won't run CoffeeScript directly, but there's no reason that you can't compile Coffeescript instantly on your PC, and then send the JavaScript to be executed,
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
If there was a coffeescript REPL (I guess there is?) you could probably modify it to send the code you write direct to Espruino - a bit like in the implementation of https://www.npmjs.org/package/espruino-cli?
Espruino won't run CoffeeScript directly, but there's no reason that you can't compile Coffeescript instantly on your PC, and then send the JavaScript to be executed,