I used to work on Mozilla's data platform. That stuff is all open source. See e.g. https://github.com/mozilla/gcp-ingestion/ for the ingestion pipeline, https://github.com/mozilla/bigquery-etl for queries/ETL, and https://github.com/mozilla/looker-spoke-default/ for looker model definitions for that data.

Also go read the docs at https://docs.telemetry.mozilla.org/. Those will give you insights into every way they use data.

I've never seen a company that's more open about their data usage.