The Databook states that it's a Kekkei Mora Taijutsu, therefore, it's obviously on a much higher level compared to what the Byakugan normally provides as it's just a KKG and this is only made possible through Kaguya's Mastery over Chakra. The effectiveness stems from her mastery over chakra, thus, determining the amount of chakra is dispersed within the palms and the Databook outright states that it has the potential to become the strongest offensive ability through usage of her Perfect Dojutsu, so we can conclude that it's Kaguya's Mastery over Chakra and her RinneSharingan that determines the effectiveness of the technique.
How the technique functions obviously originates from the Byakugan as it's something that Hyuga's possesses, but Kaguya's shouldn't be compared considering she has the best level of chakra control in the entire manga, the highest level of chakra in terms of quality and quantity, and a RinneSharingan to boot. We can't just claim that the Byakugan is superior to the Sharingan without taking into account these factors.