QtWebkit has QWebInspector which allows to easily attach inspector per QWebPage, which is very useful in applications that allow to use multiple views, usually web browsers.
Currently QtWebEngine is supposed to allow remote debugging, but there seems to be no documentation on how to use it and how it would work with multiple instances QWebEnginePage, without forcing end user to select which page should be inspected.

Chrome / Chromium allows to have separate inspectors per page which is very handy and simply works.

I would suggest to add subclass of QWebEngineView or QWebEnginePage that would have extra setter that would allow to attach page to be inspected.