At the moment we don’t have any plans to implement this. It sounds like it’s mostly useful for learning/training? If there are other ‘production’ scenarios that you think it’d be useful, where a regular table/matrix wouldn’t work, please let us know in the comments!
At the moment we don’t import custom objects (we have to request specific things through their API) but we could improve this in future.
We could also import custom fields on their standard objects.
Who else would find it useful? Please add your vote if you would!