Any particular reason you don't tag the objects instead? That's a significantly lighter-weight operation, since S3 doesn't have native renaming capability.
In HopsFS, you can also tag objects with arbitrary metadata (the xattr API), and the JSON objects you tag with are automatically (eventually consistent) replicated to Elastic search. So, you can search the FS namespace with free-text search on elastic. However, the lag is up to 100ms from the MySQL Cluster metadata. See the epipe paper in the blog post for details.
You can't list objects by tag.
IIRC, you can, but it's bit elliptical: because IAM access policies can key off tags, you can adopt an IAM role that can only see the desired tags, and list objects.