https://mycroft.ai/

Mycroft has a lot of native skills and abilities baked in and, since it is open source, it allows outside developers to add more features over time.

Video: https://youtu.be/m4L0QfzUeEI

Github: https://github.com/MycroftAI/mycroft-core

Docs: https://docs.mycroft.ai/development/getting.started