Well, yes and no. They are implementing a rendering engine that supports things the web famously doesn't support, which includes fundamentals like UITableView from iOS. They are doing this by leveraging new APIs to access what browser layout engines do under the hood. So in that way, it generates native browser elements, and their API is declarative. So it's at least one abstraction layer below React and friends.

....no and no. The call was for a declarative interface to the DOM, like React, built into the browser. Flutter, being not built into the browser, is not that.

There are a million things that do this already - including Qt, which already works in WebGL. The point is to leverage the rest of the web's existing features while also getting declarative templates, not to create another Flash.

Flutter/Hummingbird will be writing DOM elements, so it's not just an opaque WebGL texture.