Searching / slicing a serialized json field in dataset

I am working with sedthh/gutenberg_english · Datasets at Hugging Face

I’m looking to be able to drill down in this dataset’s METADATA field, which is serialized JSON.

For example, I would like to be able find all rows where Metadata locc == “PS”.

But I have noticed that when I try to slice within Metadata, it’s indexed by character. I can’t go to a specific subfield without some extra tool to read that field as serialized JSON.

Does anyone have an example of how to do this? TIA!