-Sakura is far useful than most if not all OP females
- top tier medical ninja
- looked stronger than Naruto at beginning of shippuden
- beat Akatsuki when kage level characters got easily beat by Sasori
- was useful in the war by healing everyone and keeping Naruto alive
- surpassed 1 of the Sannin
- Probably physically strongest in the verse
- Has temporary immortality
- has so much chakra reserves that it's possible to travel dimensions
- was pivotal in beating Kaguya (final villain)
Nami fans would jizz if Nami could even accomplish 5% of what Sakura did in Naruto or even be relevant in the story the way Sakura was.
So far Nami's only purpose is to read a literal arrow pointing to another island and act as a damsel in distress. Literally useless
And yes, Sakura would easily beat Big Mom 1v1.