The British royals typically don’t bring young children to ceremonial events, although there were several of the older great-grandchildren at the memorial service for Philip (not his funeral, but the larger service held more recently, which was more like a regular church service). I would think Archie and Lilibet would still be considered too young (Louis, the Cambridges’ youngest, was not at the service for Philip and he’s older than Archie). I wouldn’t be shocked to see George attend as part of the direct line of succession, he is starting to take on royal duties, but I would be surprised to see him walk in the procession behind the coffin … yes, William and Harry did for their mother, but they were older and it was a different time. I don’t see William putting him through that.
I don’t imagine any of the younger children will attend. You’re right, though, that Meghan in particular will be criticized whatever she does. Once_upon was criticized for bringing her young child to a family funeral. I got yelled at for NOT bringing my young child to her grandmother’s funeral, an event we knew she would find upsetting and confusing. You can’t win, and that’s true of Meghan more than most.