There is a way that this could be done with the current API
If you wanted to make a game in which people need to find "keys" to open dungeon doors for example to progress to the next level.
You could use in-game assets as the keys themselves.
Think of it like this, you could hide a skull somewhere in the level that the player needs to find, the skull could then be placed inside a chest that is near a door, when the chest contains, in this example a skull object, the door is unlocked. Removing the skull from the chest will lock the door again.
You could also use things such as touch mounts that require torches in to unlock doors. You could implement this in a kind of riddle, where certain torch holders need torches and others don't in order to unlock the door.
It's all very possible, you will just need to think carefully about how it is coded.