Secret Items in Minecraft Bedrock Edition

Here are a bunch of secret items in Minecraft Bedrock.There are 4 chests with a bunch of secret items inside.There are secret items that everyone knows how to get, like the command block and structure block.There are also secret items that pretty much no one has, like tile.client-request-placeholder-block.name. (I used hyphens instead of underscores because it will make the text in italics)