What kind of functionality do you want to add? The software is written in a modular way and it is not too hard to extent it. Please reach out to us via email and then we will help you to extent the library.
I'm sorry to hear that you are sad because you wanted to contribute but can't. Maybe, we can find a solution to that. If you want to contribute (e.g. by joining our team), feel free to reach out to us! We are always happy to have capable and driven people on board :)