Yea that wasn't clear. The article made it sound like they're aggregating data from various sources that collect location data (probably from those app metric p

Yea that wasn't clear. The article made it sound like they're aggregating data from various sources that collect location data (probably from those app metric providers like Tune and others). So if someone ran an open source phone with F-Droid or just installed zero apps with metrics (and Google isn't one of their sources), they wouldn't ever show up in this data set. I'm guessing location data comes from the Apple/Google location APIs that can map peoples aprox locations based on their proximity to Wi-Fi points (I think they register Wi-Fi points and then the first GPS signal the phone gets after; like when someone walks outside, and use a set of those to get approximate triangulation for indoor Wi-Fi APs).