https://www.patreon.com/posts/i-roll-with-soul-69607684
The skateboard in that link is an accessory that's attached to the wrist and the sim can walk around with it. But when posed with pose player, the accessory ends up under the feet, like he is riding it. How does it change position like that just for the pose? If I want to make other poses with the skateboard, when imported in Blender, the skateboard attaches to the hand of the rig. I can drag the skateboard mesh down under the feet either in object or edit mode, but when exporting the new pose into the game, the pose works, but the skateboard remains floating at the hand like an accessory and does not go under the feet. As another example, maybe I want to make a ball-throwing pose with a ball accessory, but it has to look as if the ball left the hand, maybe a foot or two from it, but in the game it stays stuck to the hand. I can't find a tutorial anywhere that would explain how this creator did what he did. That skateboard is not an object, it is an accessory. One time I wanted to make it seem as if drink cup accessory fell from a sim's hand, so in blender I dragged it down and imported the pose, but in the game the cup remained in hand.

You might want to move it in pose mode.