Harry used to hate the Crown and said that he'd make sure the series was shut down before it got to issues addressing his life. But anyway.
Celebrities that have a product they produce like music or films can rely on those products for promotion. But Harry is now more of an 'influencer' like a Kardashian or a Jenner - the product to promote is himself. The reality of promoting yourself as the product is that it requires constantly putting yourself out there and inviting people in.
I think the difference with the royal model is that when Harry has money to make and products to sell, all public appearances are going to be hinged on business interests. Even these documentaries and podcasts are going to be all about money and ratings, as Netflix will need a return on their enormous investment and advance payments to Harry. I don't know if charity with a $200million + pay day is really public service. It's just celebrity culture.
But there is certainly a huge appetite for celebrity culture. Beats me why people love the Jenners and Kardashians, but enough people seem to do and hence they have become extremely wealthy and famous from it. It's likely that enough people will enjoy Harry and Meghan's celebrity to enable them to make a career from it in the same way.
The thing that will annoy me is if Harry & Meghan start acting holier than thou about it. Honestly, the incredible wealth and platform they have is based on a system of extreme inequality and hereditary privilege. They are not self-made people and a part of the 0.001% of privileged society. So a bit of humility would go a long way.