According to the Playdate SDK documentation, "The compiler will automatically copy your game’s metadata from your project folder into the resulting game." My resulting .PDX file has the pdxinfo file inside it.
Your zip file has the treasure.pdx folder inside a folder called treasure, which means when you try to sideload it, it says it can't find the pdx file. It works if you move the treasure.pdx folder to the root of the zip.
