Harry will absolutely hate having sit out yet another Christmas in Montecito. But I suppose it's their only option to try and save face.
I do feel terribly sorry for his children, when you think of all they are missing at Sandringham. What a rich inheritance (not speaking in monetary terms) of extended family, family history, cultural heritage, tradition, love, meaningful connection, belonging and unity they are missing out on. Cousins, grandparents, connection to their father's own childhood, one half of their heritage. All in such immense privilege and gloriously beautiful surroundings. I expect Harry cannot bear to acknowledge what he has deprived those children of, if he has the capacity to understand the magnitude of it.
Meanwhile they will be flown back to sit in their echoey, empty, souless mansion with whatever excessive materialistic rubbish Meghan inundates them with, in yards of horrible neutral wrapping paper. In the very state where another grandparent sits incapacitated, probably in pain, possibly alone - never having met his grandchildren.