Like Pip, Mrs. Pocket was destined for greater things, but both end up basically useless. Mrs. Pocket’s father wanted her to marry up, and Pip’s sister wanted him to be bettered by his association with Miss Havisham. Neither plan was successful.
Apparently Mrs. Pocket’s father felt that he had been denied a title from his own father. He was a knight but died early. He wanted his daughter to rise higher in British society.
[He] had directed Mrs. Pocket to be brought up from her cradle as one who in the nature of things must marry a title, and who was to be guarded from the acquisition of plebeian domestic knowledge. (ch 23, p. 130)
As a result, she “had grown up highly ornamental, but perfectly helpless and useless” just like Pip. Pip is given his great expectations by a secret benefactor and sent to London to become a gentleman. He learns a few gentlemanly things, but remains, like Mrs. Pocket, basically ornamental and useless. He has no actual trade, and knows very little about being a grown-up.