I’m not saying it’s a WebView, but obviously it works extremely similarly. It is not a native app framework.
It's easy, instead.
It may render native components, but those components are still controlled by the non-native runtime, thus extra baggage.
It would definitely be using native UI components, which a normal web browser won't give you via the rendering engine.
But that's as native as it gets. The control logic for how those components operate outside of how they're internally built is likely done w/ React / JavaScript, instead of native.