And it could definitely be extended, but I think that if you're writing something that you want to integrate with the Espruino firmware on any more than the most basic level, you should probably just build your own firmware and it'll save time in the long run.
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.
Yes, we'd talked about that - and it's definitely possible, but I can imagine it'd be pretty easy to end up using the wrong file.
Right now we have this table for exports: https://github.com/espruino/Espruino/blob/master/src/jswrap_process.c#L74
And it could definitely be extended, but I think that if you're writing something that you want to integrate with the Espruino firmware on any more than the most basic level, you should probably just build your own firmware and it'll save time in the long run.