Population Coverage of GWS U.S. Mobile App Engagement

Hi,

I am curious if you have any information about the total sample size of the panel/population covered in this data: https://app.deweydata.io/products/ce21c475-0c25-4093-acd2-f74045532e01/package.

Corresponding data schema here: https://docs.deweydata.io/docs/gws-us-mobile-app-engagement

I downloaded and summarized the one-month GWS U.S. Mobile App Engagement data (2021-01-01). I found around 27k and 24k unique users (identified with unique "DEVICEID") for Google chrome and Facebook, the top APPs with the largest user counts. This means the data only covers at most 27k users (of Google chrome) around the US in the whole month 2021 January.

It would be helpful if you could provide any sources where I can check for details of how many devices are included in the whole panel.

Thank you!