Notably, this is going to manage your data in it's native format (i.e. you can actually read-write the files out of the S3 bucket as if they were actual objects

Notably, this is going to manage your data in it's native format (i.e. you can actually read-write the files out of the S3 bucket as if they were actual objects, mapping 1:1 to each file). The ZFS backend is (almost certainly) a block-based format that is persisted to S3 (meaning that you cannot use it for existing data in S3, and you cannot access data written through ZFS via S3).