Camilla also did not set out to purposefully denigrate the position to which she hoped to one day rise.
That is the key difference.
Harry and Meghan made the extraordinarily foolish decision to go around telling everyone that being Royal was really not all it was cracked up to be, that a life of Royal privilege was undesirable, nothing special, rather plebian. That being an heir to the throne of England was in fact, a disabling hindrance in life, a cause indeed of suffering. They spent a great deal of effort metaphorically disrobing themselves in public until like the boy in the Emperor's New Clothes, everyone could see they were naked.
Why didn't it occur to them that their major advantage to any future ventures, to their social and networking currency was their Royal mystique?
It's just plain stupid to try and sell bananas to the public whilst simultaneously saying that bananas suck! Same with your Royal status.
That this didn't occur to them a very long time ago when they decided to take the 'reveal the dirty laundry for cash' route is odd. That was always going to be a short term flash sale.
Now they gave realised that nobody wants to buy that anymore and they need to build back that Royal glamour.
But the spell has broken for them.
Camilla on the other hand could be rehabilitated because she still supported the idea of Royalty, allowing the Royal PR team to retrospectively create a narrative of the greatest love story ever told between a future King and his prior preferred, but lost bride. It has worked.
At this point Prince Andrew has more realistic prospects of rehabilitation in the UK with Virginia Guiffre's unfortunate demise than H & M
But Americans are less unfavourable towards them. It's possible a rebrand may have more traction there..