I see your point about Diana being a true aristocrat with a very specific sense of her place within the monarchy and the traditions that came with it. There’s no denying she was deeply rooted in British culture and had an innate understanding of the royal system—something that could’ve made her cautious, even skeptical, of Meghan.
However, Diana was also someone who had experienced the pressure of the royal machine firsthand and understood the isolation and media scrutiny that comes with it. While it’s true that Meghan's way of navigating the world might seem at odds with Diana’s upbringing, I think Diana would have at least recognized that shared sense of being "outside" in their own ways. Diana didn’t fit the mould either, did she? She carved her own path, often at odds with traditional expectations.
As for Meghan and her role in the family dynamics, it’s clear Diana would have been protective of her sons, especially in the context of what we know about Harry's relationship with William. But I think Diana, with her own history of feeling pushed to the sidelines, would have also had compassion for someone who seemed to struggle with the same pressures. Could she have accepted both of her daughters-in-law fully? Maybe not in the way we might expect—Diana wasn’t a saint, after all—but I think she would have understood, on some level, what Meghan was up against, even if they had differing approaches to it.
Ultimately, it’s impossible to know for sure, but I do think Diana's empathetic nature might have led her to see something in Meghan that wasn’t immediately obvious, even if she didn’t approve of every decision. And as much as Diana loved her sons, I believe she would have wanted them to find their happiness, even if it came from unexpected places.That said, if she had lived both the sons may well have bloomed in differrent ways than they eventually did and probably better for both.