I think those ones are found in https://github.com/discourse/discourse/tree/main/app/models/concerns/reports, though may not be as easy to decipher as some of the ones shared in data-explorer topics.
There are some good tricks in this topic too for some of the Data-Explorer automagic you can leverage to make the results more interactive:
If there are any queries in particular you’re trying to create feel free to spin up a topic and ‘think out loud’, as we’re always looking for more examples we can add to our community pool.