The credentials on the block are optional so this should work. You may also check the blocks from the prefect-aws collection - there are blocks there like S3Bucket
https://github.com/PrefectHQ/prefect-aws/blob/main/prefect_aws/s3.py#L232
or you can do:
import fsspec
fs = fsspec.filesystem("s3")
fs.put("/Users/anna/repos/dataflow-ops/docs", "<s3://prefect-orion/docs>", recursive=True)