Don't know why you're taking this so srsly, but aight.
Overthrowing the government just feels like the means to achieve the dream of world peace and building a more stable union to be put in its place which is something Vivi could go for as a dream goal, a better world free of corrupt tyrants, especially after having experienced that sort of corruption firsthand. And going back to Alabasta now would just put her country in danger, assuming Imu doesn't have it Lulussia'd anyway because of some big brain Lorosei logic.
Sabo will only tell her that she's a D and that Imu hates Lily for spreading the glyphs. There's still a lot left that's still unknown about Lily and her history that Vivi can learn.
Luffy is the catalyst. Knocks down the WG and Vivi builds a better coalition or union in its place that's not under the authority of just one king or inbred nobles, thus fulfilling the original promise that should've been kept by the first 20 kings.
ViviForNakama
Also CarrotForNakama because
@Pot Goblin has great tastes.
I hope not too. The Gorosei should each face different opponents, but LOda might be crazy enough to do give them all or at the very least 3 to Luffy.