There are several details people may be wishing Oda had touched on during the actual Wano arc, but held back presumably because he felt it wasn’t
time to elaborate on them yet. I’m talking about examples such as:
Chopper’s concern with the SMILES - Could have been addressed in Chapter 943, but isn’t addressed until SBS Volume 105
Bepo’s Sulong form - Had an opportunity to transform in Chapter 995, but doesn’t do so until Chapter 1081
MADS - Mentioned by Queen in Chapter 1017, later shown on the cover of Chapter 1068
Zoro’s lineage - Speculated on in Chapter 1023, but not elaborated on until SBS Volume 105
Tama’s lineage - Graves of her Kurozumi parents are shown in Chapter 1051, but aren’t elaborated on until SBS Volume 105
One detail I’m thinking of is Zoro visiting Ryuma’s grave. He said he’d visit it in Chapter 954, but still has yet to be shown actually doing so.