That’s not necessarily that easy, if your original Datasets lazily loads the data.
Currently Subset only uses the passed indices to forward them to the underlying Dataset.
This works fine since Subset has no knowledge about the Dataset and just acts as a “filter” for the indices.
If you want to forward some dataset internals such as .classes, .targets etc., Subset would need to know what kind of Dataset you are using and which attributes to expose.
Your underlying dataset can of course be a custom Dataset, which doesn’t provide these attributes as they might be unknown during initialization.