[pietro]

It depends. In our current app, all we needed to implement separately was the margin for the status bar, literally two lines of code.

But as we move further, we'll be looking into making the versions for both platform feel truly native, and that will require some changes to navigation components and the overall navigation paradigm (tabs vs. drawer, screens vs. cards etc.).

The platform differences are as much about design as about code, and I don't see how you can escape that work with any cross-platform framework. But React Native makes it very easy to implement in a way that lets us share all but a few components.