It's somewhat of a dark art. The platforms themselves...

It's somewhat of a dark art. The platforms themselves approximate the numbers. So, ZOLEO for instance can share their actual downloads with a platform (such as AppAnnie) in exchnage for a premium subscription including insights on competitors etc). Once a few different apps do this they can approximate numbers.

Remember a ZOLEO download doesn't equate to an actual sale of a device, nor subscription. A non-ZOLEO user can use it to communicate with someone out in the field. Similarly someone who downloaded the app a long time ago (like me), may commit to purchasing a device or a plan at a much later date.

I just treat it as a reasonable guide of probably success. It's also good to track things like price changes, seasonality, launches into new markets etc.

I've also found in the past that iOS (are far more important than Android). I'm not sure if adventure customers skew to being Apple, but invariably wealthy people do. Mind you, with ZOLEO they seem to track fairly evenly.