Comment by jorams

> they aren’t directly using WebKit, but rather WebView, a cross-platform API that delegates rendering to the OS preferred rendering engine, which on Apple devices happens to be WebKit.

WKWebView is a part of the WebKit API, so it always uses WebKit. As far as I know it's also a Cocoa API, so it's only cross-platform in the sense that it's available on both iOS and macOS.