It's NOT Open Source.
"There currently isn't a release date scheduled for the other voices"
[1]: https://huggingface.co/blog/hexgrad/kokoro-short-burst-upgra...
- Apache 2.0 weights in this repository
- MIT inference code in spaces/hexgrad/Kokoro-TTS adapted from yl4579/StyleTTS2
- GPLv3 dependency in espeak-ng