I agree with much of what you’re saying but I have to disagree with this:
Her undoing was her unwillingness to bend to royal protocol. Her insistence to do things her way. Her inability to stay mum on the things the press said about her. Perhaps one of the biggest nails in the coffin was when she refused to come out for pictures at the hospital after Archie was born. A barbaric practice for sure, but one that royals have partaken in for decades
At the point she delivered their baby, she had already been in a severe mental health crisis. The targeted and very racist press abuse was already far beyond anything even Diana had to endure after Charles minions turned openly on her. It’s interesting that you (and many others commenting) think that it was Meghan making all the decisions for the couple. In fact it was Harry who had been pushing back against the palace machine and who decided to get his family away from it, only after his beloved, saintly, grandmother, father, and loving brother (yes I’m being sarcastic) refused him the help he was asking for.
Unless of course you think Harry is a big liar.