The post Sargon gave his daughter was not honorary. The en priestess of the moon god Nanna at Ur lived in the giparu, a walled residence beside the temple, administered its estates and its personnel, and stood in the ritual relation to the god that the title implies. Installing an Akkadian princess in the most prestigious Sumerian priesthood of the south was a political act carried out in a religious form, binding a new northern dynasty into the ancient cult centres it had just conquered. It worked well enough that royal daughters went on holding the office for centuries afterwards.
The physical evidence is thin and real. A carved alabaster disc excavated at Ur shows a procession before an altar with a woman in the flounced garment of the office directing it, and the inscription on the reverse names Enheduanna, priestess, spouse of Nanna, daughter of Sargon. That disc is why neither the office nor the person is in question, whatever is argued about the poems. It was found broken, and apparently broken deliberately, which fits the account of a revolt against her that the poetry describes.
The giparu itself has been excavated. It held a shrine, a burial ground for the priestesses who had served there, kitchens and storerooms, and it was rebuilt more than once across the many centuries the institution lasted. Later kings kept up the practice of installing a daughter in the office, Nabonidus of Babylon among them, nearly seventeen hundred years after Sargon, which makes this one of the longest running religious offices attested anywhere in the ancient Near East.