I was actually tasked with building essentially this same thing back in 2014 when I was a junior dev for a fintech startup. They needed an anonymized version of prod database suitable for support team to pull up when trying to reproduce bugs. Did this gigantic thing that would stream the db dump into a C++ app and anonymize it on the fly. Took a similar approach to their masking they do here. Fun project. Company should have productized it.

This is the exact usecase that we are building for with Neosync (https://github.com/nucleuscloud/neosync)