Yugi and Goku both posses an object that reminds them of their Grandpa.

Goku possesses the Four-Star Dragon Ball that once belonged to his late Grandpa Gohon. Goku keeps it as a way to remember him.

Yugi carries the Millennium Puzzle, a treasure that he got from his Grandpa when he was young. Yugi tells Anzu that his puzzle is a memento of his Grandpa. This causes Anzu to think that Yugi’s Grandpa is dead, but he is not actually dead. This contrasts with Goku’s grandpa who is actually dead.

It’s important to note that Yugi directly mentions the Dragon Balls, meaning that Dragon Ball is a real thing in the Yu-Gi-Oh! universe, and that Yugi has read/watched it. Perhaps Yugi is getting carried away by his Dragon Ball-inspired imagination and is planning his puzzle to be a memento of his grandpa well before his death occurs.