This is quite great, looks good. Curious to see what code it generates.
The primary focus of Comet is on design and prototyping, not on generating apps directly. You'll be able to export production-quality assets for handoff to developers, or view interactive prototypes online / on devices.
That said, Comet will have an extremely powerful plugin architecture, so third-party developers in the community could certainly create plugins to export code for Angular, React, Objective C, etc.