Yes. The conflicts between Sanji and Luffy in the manga often stem from complex circumstances and character developments that drive the narrative forward.
Luffy uses Gear 5 in a significant battle towards the later part of the manga. But the exact chapter or arc can vary depending on how you're reading it.
A scenario could be that the 10th walker has been following the fellowship secretly in Moria. When they finally reveal themselves, the fellowship is shocked. If the 10th walker is a skilled healer, they could tend to the wounds of the fellowship members who got injured in the mines. Or, the 10th walker might be a wizard with powers different from Gandalf's. Their magical abilities could either be a great asset or cause some unease among the fellowship.
The encounter of the 10th walker with the fellowship at Moria in fanfiction can be very interesting. The 10th walker may bring a new dynamic to the group. Maybe they are from a different race or culture that the fellowship has not encountered before. This could lead to cultural exchanges within the group. For example, they might have different ways of fighting or different beliefs about the dark forces in Moria. Their presence could also change the power balance within the fellowship, either causing some tension or strengthening the group as a whole. They might have a special connection to the ancient magic of Moria, which could be crucial in helping the fellowship overcome the many obstacles they will face in that dark place.
Luffy is still alive and kicking in the manga. The story keeps evolving with him at the center of the action, encountering new enemies and growing stronger.