What I actually wanted to ask is whether it’s possible to view cards that have entered the out of play area…

It depends on if the cards are still in the game or out of the game. Stolen Memories is designed around hidden information both mechanically and thematically; the cards placed beneath it cannot be viewed by the player, and although these cards are “out-of-play”, they are still “in the game” and can be interacted with by discarding the obligation. Pirate Lackey is different. Once it removes a card from the game, the card is not “in the game” and is not beholden to being hidden information. The player is allowed to view the removed card and get a sense of how their deck changed.