Agree completely with @Want2bSupermum
We had some Americans at my university and they had to undertake an obligatory British culture course
It feels like no one has given her the basics and that it is not simply an elevated celebrity role but a formal State role in line with being wife of the Vice President say.
Not that the current Executive Branch has any example to offer but Jill Biden is a good example of what's expected from her.
Another good example is Doria at Christmas.
Though I think it's wonderful she has been asked it will have come via request, a request Kate, Sophie and Autumn would never have dreamt of asking, because it simply isn't done. Asking Meghan herself last year was a huge departure, and neither Kate nor Jack Brooksbank were ever extended such an honour. Presumably neither William or Eugenie would have dreamt of asking.
But I am glad all the same, I think it's lovely but it does show a gap in customs and a lack of understanding, presumably Meghan is applying what would be the norm in the average family to the RF without realising the distinction, her mother isn't being asked to Christmas with her son in laws granny, she's being asked to Christmas with The Sovereign and those are the sort of distinctions I think Meghan lacks.