But sabo is on the cover, I know oda is underplaying her massively but they wouldn't do it in the game too right ;-;
It's not like she got shafted in favor of others. The Dressrosa chapter omits almost everything from the canon story. The manga was about 1/3rd through the arc by the time the game was locked down for content.
I imported and cleared the story + majority of the content, if you have any other questions.
Edit:
Is there cross-platform play between versions? For instance, Dynasty Warriors 8 Xtreme Legends allowed Vita and PS4 play with each other online.
I could be wrong, but I don't believe there is. The Vita version has abysmal performance compared to PS4. To the point where the S rank goals are actually reduced because the enemy count is much lower.