I run pihole on a Raspberry Pi3 at home and you'd be wowed at the amount of dialling home all devices so, and metrics. With a network of Apple iPad/Mac, Windows and Android devices, it's over 25% of all DNS requests that I block.

Useless once you take your phone off WiFi of course, but still baffling the amount of metric abuse going on, and entirely without warning (am within the EU so concerned by it!)