Not purely WYSIWYG because you can't arbitrarily place anything anywhere. It seems to be based on SwiftUI and carries over a lot of those concepts into the builder.
Since our SDK is rendering native SwiftUI we decided the best experience would be to surface the API of the underlying layout system in a visual way. Similar to how Webflow surfaces HTML/CSS.
Of course this meant building a SwiftUI renderer for our Android SDK. We are considering a future release where the Mac app exposes both SwiftUI and Jetpack Compose to allow a full visual build experience that is 100% native to both platforms.