It's not advertised in the documentation, but HeadObject(Bucket, Key)['Metadata'] is a neat dictionary of custom values.
0: https://docs.aws.amazon.com/AmazonS3/latest/API/API_HeadObje...
Perhaps I don't understand what you're saying fully though--as I don't fully understand your comment.
https://docs.aws.amazon.com/AmazonS3/latest/dev/UsingMetadat...
It's not advertised in the documentation, but HeadObject(Bucket, Key)['Metadata'] is a neat dictionary of custom values.
0: https://docs.aws.amazon.com/AmazonS3/latest/API/API_HeadObje...