Yes, you can actually try out a sample project without the Sketch file - After signup, select "Create sample project".
Then go to Code-mode and pick any part of the design to get React code. Developer 101: https://www.animaapp.com/resources/anima-101
In Code-mode, there's a settings icon, you can pick functional or class-based components. The idea is to have more settings coming, like styled components (CSS in React) etc.
Regarding Speed - Yes! once you've synced a design file (may take 1-2 minutes for multiple screens), you can pick any part of it and get React components code in 1 second.
Let me know how it works for you, thanks!!