This is a very good use case and Thank you for your patience while we worked on this requirement. This can be achieved using the Inline processing and I have created a Knowledge Base article so that it can help the other community members with similar requirements.
Hi @saikanumuri ,
Is it possible the inline preprocessor will not evaluate for attribute uniqueness? I imported two new users from CSV and the preprocessor generated the exact same value for both records. Repeated with three more records and got the same value in all records. Repeated with 5 records and got the same behavior. Please see attachment for details...