Hi Micro,
If you have a google-oriented phone you may be able to install a new ROM, with the Google data collection code stripped out and only the open source Android core remaining. That can get a lot of privacy and control back. Of these, Graphene is likely the best and certainly the best in terms of privacy. http://itsfoss.com/android-distributions-roms/
Unfortunately, you are then left with a phone which may not have a lot of functionality left, as things like voice recognition and GoogleMaps are hard wired to Google. And many of the most popular alternative apps either use the Google services indirectly or are in the data harvesting /grooming business themselves.
So, after considering Graphene, e/OS (all derived from LineageOS, which is open source), and some Linux phones (pinephone, Librem5), I concluded none are very useful right now for most people, including me.
Which sticks me with Apple and iOS. It may not be perfect, but Apple has the highest functionality combined with approximately the most security/privacy credibility possible in this dystopic world. You can micromanage services to a level far beyond what Google allows, and Apple has a solid history of banning companies which are caught breaking the privacy rules.
Eventually I expect there will be a really great Linux phone alternative with all the underlying services under open source as well. I will buy one; actually I did buy one, but it is not ready ready for release yet.
Until then, Apple with full service, or something like GrapheneOS (Android with the Google Skinner Box code stripped out), are the only choices a self respecting person should even consider, if they want to keep their soul.
One last comment, to anyone who may be thinking Andoid and other things like Amazon Alexa/Echo can't really be that bad. You should be catching on that Our Masters have been grooming us for decades. They haven't really begun raping and rounding us up yet. But really soon....