Hi Brent,
Why not the REST API to upload files to the S3 BUCKET, https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-post-example.html?
Another alternative is to use the AWS SDK for Java by writing custom Java code (by passing in the needed data etc), some example; https://www.baeldung.com/aws-s3-java
You can also run the PY script via a Java action (instantiating through the OS/CMD etc), but it requires a lot more effort, which is in this case not recommended I think.