Update: 7 days later, I've finally finished the puzzle. : r/Cuphead
Amazon.com: Youtooz 1000-Piece Cuphead Jigsaw Puzzle, Official Licensed Collectible from Cuphead Video Game, by Youtooz Puzzle Collection : Toys & Games
Cuphead Graveyard Puzzle Solution / Tutorial - Over 30 Solutions! - Secret Boss - Broken Relic - YouTube
Cuphead Broken Relic: How to solve the Graveyard puzzle | PC Gamer