Oprah is an actress and a talk show host, she is also Meghan's friend. There was no way she would've asked any questions that weren't scripted first and agreed on. Both ladies are actresses.
It was very much Megan's gig, with Harry as an afterthought (brought in at the end to give Meghan credibility) I'm not convinced he had much control over what she said (I think she does and says exactly as she pleases)
She was talking to the American audience, referring to 'Kate' and 'Fergie' which are not their names and not what their family call them (but rather what the American public know them as)
She lied about why Archie is not a prince yet - and the American public didn't know any better, they took her word for it (did Oprah do her research? Of course she did! Did she know Harry's children would never be princes & princesses on birth regardless of who he married? Of course she did....but the truth didn't make for an exciting interview did it?)
I do believe someone asked how dark their children would be, maybe in an ignorant way, maybe in a more malicious way...who knows. It isn't an appropriate question and one that hopefully was challenged and shot straight down by Harry at the time. That should've been dealt with at the time within the family privately. I don't think airing that private conversation (without saying who it was and giving them a chance to defend themselves or even publicly apologise) is anything but slinging mud.
I believe Harry is in over his head, he loves her and is building a family with her but she is a loose cannon, very ambitious, arrogant and always gets her own way - he's stuck on this rollercoaster with her now and I don't think he can get off! I don't think he realised how much he'd lose by stepping away, I don't think he ever considered he'd lose his military titles or any income - It's all come as a big shock to him.