I strongly encourage anyone concerned about their privacy to start using a firewall that filters (or at least monitors) outbound traffic by default. And not just the packets, but the web requests.
You would very likely be alarmed by what your phone is doing and who it's talking to without you knowing. iPhone or Android.
It's mostly Open Source with some proprietary bits sprinkled on top. It also comes with AV software, though I won't speak to the efficacy of said AV software.
I would like to build an equivalent fully-FOSS system, but haven't had time to do that yet. It would of course need to be Ansibled (or equivalent).
You would very likely be alarmed by what your phone is doing and who it's talking to without you knowing. iPhone or Android.