People make fun of Usopp because he is a coward, while not understanding his motivations and his character development: you can’t be truly brave if you aren’t afraid. Everytime Usopp is terrified, he somehow ends pulling himself together and actually contributing to the mission. And his cowardice has been crucial for the Straw Hats victory multiple times already.
The Straw Hats crew is united by their common goal: help Luffy become King of the Pirates and fulfill their own individual dreams. I seriously doubt any crew member will fulfill their dreams before Luffy becomes the King of the Pirates. So why would Usopp?
Usopp will not stop being a coward until the end of the series, because his goal is that he wants to be a brave warrior of the seas.
He is the only member that has a dream that is not a tangible item or something that can be acquired after clearing a specific objective. It is a dream about self acceptance. He wants his tales to be told by others. He wants his lies to become true.
He won over Perona because his self esteem was the worst. One day he will go back to Kaya full of stories that are true, he will no longer be a liar because he no longer needs to be one. He will be able to see Yasopp face to face with mutual respect. But he still has to grow for that.
Elbaf being sniper island is incredibly fitting. And I believe his character arc in Elbaf will be related with improving even further his ability as sniper. And part of this is learning to calm down and control his emotions to improve Observation Haki if he wants to stand a chance against the likes of Van Augur. The Giants would instantly love Usopp as they will recognize him for honoring Sogeking and this will be pivotal for his story arc, plus we know Dory and Broggy are back home and also Oimo and Kashii. He will realize he already has plenty of fans, and this admiration from the people he looks up the most, will boost his confidence.
I think Usopp will leave Elbaf with new powers and better self confidence. He will start to believe that he is capable of being a member of the Pirate King’s crew of his own right. And this will start triggering the change that will eventually lead with him fulfilling his dreams.