You can only truly appreciate the Uub/Pan ship by understanding the historical dynamic between the modern black man and the modern white woman. Uub is:
>black
>poor
>unsophisticated
Which makes Pan's classist and racist parents who come from prestige and wealth turn up their noses at Uub. However, Uub has tons of social charisma and has a variety of talents, which many girls (Pan included) find very attractive. I imagine their first few years of consorting will have Gohan/Videl staunchly opposed to the relationship saying that Uub is beneath Pan in every way, shape or form (which Pan will cheekily reply that he is often beneath her to their disgust). They'll ask Pan to try that nice incel boy of Bulma's but be given a sharp no for an answer.

They'll then turn to Gohan's father, Son Goku, and see if he can bring some sense to his granddaughters mind but be flabbergasted when they discover he's given his full approval. Gohan and Videl will try to barricade Pan into the house only to have their efforts turn in vain for Uub learned teleportation off his teacher.

Eventually after a few years when Pan will start popping out little caramel babies they'll slowly come around to it and be better grandparents than they would have otherwise been to make up for their past.