All Prince Harry's interviews are with people who are entirely on his side, so that there will be no searching questions challenging anything he says. which is, of course, exactly what he wants.
However, he and his American advisors, obviously thought that if he thoroughly spilt the beans, dredged up and revealed every petty perceived wrong and lots of private details of the RF's lives, sooner or later they would be goaded into response, and that would make Prince Harry and his acolytes even richer.
Unfortunately, that is not how it works in the UK, the RF are saying nothing, long may they do it, and all that has happened is that Prince Harry has lost support in the UK. Latest surveys show the majority of people in the UK have no interest in him, or are bored and fed up by him, and even in the States interest is waning.