Hmm Meghans favourite flowers are Peonies so I go out on a limb and say (girl)
Peony
or something else flower related like Fleur, Rose, Primrose, Iris, Ivy etc.
So far shes done a lot of connect-the-dots type things. So flowers from commonwealth for her veil, blue fabric from her first date in the dress. So I think any name will have some connective value or meaning behind it.
She's a feminist so again (girl) Possibly something strong like Gaia, Ada, Ava, Ida Betty, Frida, Harriet (This would be a great fit derivative of Henry/harry and also after Harriet Tubman two birds with one stone) Xenia, Elizabeth (possibly)
She's said to be doing gender neutral parenting so a name that crosses sex or similar to another sex Charlie, Toni, Frances, Alexis, Edwina, Georgina, Roberta
Boys I think something more relaxed like Leo, Lionel, cleo, or trendy hipster Rupert, sebastian, Christopher, maximus
On the whole I think its going to have some purpose or meaning to her own life or ideals