The issue is that it has to be something extremely profound where Roger will go “no, I’m too early” since he has some kind of dream that can only be achieved as pirate king, and Whitebeard will mention how the government is afraid because “when someone finds it, and they will, everything will change…”, while also being something that can make a hardened badass like Roger and his crew just laugh themselves until they’re crying and Roger just goes “Oh Joy Boy , I wish I could meet you. What a funny story.”, especially considering that Luffy in Gear 5 is Joy Boy 2.0 with Gear 5 being rooted in freedom and laughter and happiness instead of the traditional shonen path of righteous fury about to take out anger on some force of evil.