If they really wanted to show off their credentials as progressive, non-stuffy, non-royal private citizens wanting to change the world, they could refer to themselves simply as Harry and Meghan. They're famous enough already to get away with that.
So I don't understand their insistence of clinging on to the prissy titles - the HRH, The Duke, The Duchess, The 'Sussexes' - when those are the things they say they're trying to get away from.
They clearly can't see the hypocrisy, indeed nonsense, in trying to maintain non-regal regal personas.