there’s a scene when they explain how the akagami pirate crew met uta, they find her in a treasure box after pilfering some treasure, shanks looks pretty, pretty young. The crew finds uta crying inside the box and shanks calms her by singing a little, then he has a flashback of what we can assume is him looking up and seeing roger and his crew. After that he says something in the lines of “it must be meant to be/destiny!”, so we can assume that roger did find shanks as a baby and raised him on his boat, most probably after whatever happened at godsvalley (but nothing about godsvalley is mentioned though!!). Also in the final battle luffy does use gear 5, so it might mean he can turn on and off on purpose like the other gears, thought that was interesting