What do you mean by this? I mainly use FireFox on my iPhone. Are you saying the FireFox app utilizes WebKit?
[0] https://developer.apple.com/app-store/review/guidelines/#sof...
there is no "Safari Webview" -- GP is being pedantic but he is right here. WKWebView is not Safari, anymore than Chrome was Safari before it forked off into using Blink. WebKit != Safari