Player 2 cannot use their owned skin packs but can use player 1s on split screen.

When playing splitscreen on PlayStation, player 2 cannot access their owned bought skin packs from the Minecraft Marketplace. However, they can access player 1s skin packs even though they have not purchased any.

How to produce:

Go on to Minecraft on a Ps4 or Ps5 (i believe it applies for every other console) and have a second player join a world via splitscreen. Then player 2 should go into their dressing room and open the classic skins tab to view their owned skins. If player 2 has bought any skin packs, they do not appear. However if player 1 has bought any skin packs then player 2 can view and use them.