The earliest record of Nong Yu's allusions is Liu Xiang's Biography of Immortals in Han Dynasty, which records a young scholar named Shaw History who is good at playing the flute. Qin Mugong married his youngest daughter, Nong Yu. Shaw History taught Nong Yu to play the flute, and the two of them played together to attract dragons and phoenixes. Then Nong Yu sat on the Phoenix, Shaw History sat on the dragon's back, and the couple followed the fairy. So the name Nong Yu actually appeared as a couple of immortals, but it is hard to say whether there is such a person in history.
Qin Mugong was born in 682 BC and died in 62 BC1year. Liu Xiang was born in 77 BC and died in 6 BC, 600 years away from Qin Mugong. Whether this story was handed down from generation to generation to Liu Xiang or Liu Xiang's own romantic "invention" is unknown.
In the Spring and Autumn Period, princesses didn't have their own names at all, such as Xuan Jiang and Wen Jiang. Their surnames were Jiang and Xuan, and they followed their husbands' names respectively. The former married Wei, and the latter married Lv Henggong. Daughter, married to the palace. There is The Legend of Mi Yue, which was broadcast on TV before, and there is a plot in which a princess of Chu marries the king of Qin.
So the princesses of that era were simply "political chips", either to unite Lian Heng through political marriage or as a gift to thank benefactors or woo ministers.
Therefore, a princess with her own unique name, Nong Yu, was married by Qin Mugong to a young artist with no position in music. These are probably fictional.