Yes it does and yes for iOS and Android, so in your case for macOS, no.
In 5.9, the native macOS web view is used rather than QtWebEngine and support for winrt
AFAIK, the recent version of the QtWebView module uses the QtWebEngine module for Windows. Module that is not available for MinGW currently. Also you are are using a relatively old version of Qt so first thing you should update if possible to at least 5.8.
The QtWebView module doesn't use QtWebEngine at all. The module naming is a bit confusing but that's all. QtWebView is a thin layer to use the native web view