React is pretty much environment agnostic. It supports server-side rendering because it works without a DOM. Based on how they are specifically talking about n

React is pretty much environment agnostic. It supports server-side rendering because it works without a DOM. Based on how they are specifically talking about not sharing code but sharing knowledge (i.e. same API, different components), I'd assume the environment-specific stuff is implemented by the actual primitive components (View, etc, the equivalent of div, etc, in the browser). They make it very clear that you won't be taking your web app and just magically have it work natively. You'd just write your native app using React, too.