A few months ago I blindly copied the hosts file from https://github.com/Ultimate-Hosts-Blacklist/Ultimate.Hosts.Blacklist as I was used to on BSD and Linux systems. It bricked Windows. Turns out that I had to use the installer script for Windows. Realised too late. That was my final goodbye to the Redmond giant.
For running a walled garden with iron grip, Apple allows copying the hosts file. Which I use for things like certification exams and any governmental agency stuffs.
From what I can see on the F-Droid description, Focus connects to iTunes, presumably in addition to the same places Antenna does, for podcast search indexing