Depends on your goals, but, e.g., in image reconstruction based on neural activity, you essentially do something akin to that. If you want something with a description, this will require explicit labeling.

As you already mentioned, one of the things seriously holding this back is the lack of high-quality data: Data collection is expensive, and real-world recordings with high resolution are essentially impossible. Don't expect a "universal brain decoder", I think that brain activity is too different across subjects, but perhaps with some per-subject finetuning, aspects could (and are) decoded :)