In my opinion, one of the things Wano lacked were stronger rhetorics. Just some ideas that could have added some layers:
—Stress Kaidou's racism as an oni by fully turning him into an anti-humanity. Play with how his disasters aren't human (lunarian, cyborg and fishman) and how his crew is based on zoans (maybe this way he can make his crewmates as less human as he can?).
—Strengthen Sanji's conflict with Queen by turning the latter into the engineer responsible for the factories in Wano, therefore the one polluting the water and food. Instead of just hitting a woman and insisting on Germa, this would stress Queen as a direct threat to Sanji's true values.
—Don't give Zoro the ability to cut fire out of the blue and make him develop it through his fight with King. This way we could at least get a better explanation as to how King's trick works, because it's vague as hell as it is (his fire form makes him more durable because...?).
—Make Luffy destroy Kaidou's kanabou at some point of their fight.
—Insist on how Tama parallels Kaidou as they are both lord of beasts, but contrary in the sense that one is an aggressive dictator ruling the whole country with an iron fist while the other is a vulnerable, weak kid at the bottom of the hierarchy who shows love for her animals. I'd even make her a Kurozumi in order to stress this further.
—Have Big Mom "defeat herself" by consuming her own lifespan to become stronger and stronger as she isn't aware of her oldness but is blinded by her status for decades, still thinking she's the same as decades ago and wants to show that to the new generation... only to end up too old and fragile to even fight.
—Have Luffy defeat Kaidou with a gatling that pierces his fire dragon with each punch while sending flames across the sky, some of them hitting the lanterns from the Wano citizens so they shine brighter than ever as a way to symbolize their wishes have been granted.
Just some ideas, but you get the picture.