Noob Question: If you aren't willing to deal with custom OSes like Linux (for computers) and Android Custom Roms (for phones), do you just not have any privacy at all?
I mean, exactly how invasive are default operating systems? (Like Windows, Mac, Chrome OS, Android, iOS) Do they log your keystrokes, log passwords, capture screen, upload your photos, videos, or audio? (Assuming you aren't a target of government) Is it even possible for the average person who doesn't feel comfortable messing with installing operating systems to have any privacy?
There are Linux distributions developped and maintained to be used without having to customize anything, and without any prior knowledge of how the OS works. Check out Ubuntu or Fedora for two good examples.
You can even buy them preinstalled. I generally buy my laptops preinstalled but build my workstation myself. You do not need to be technical either as long as you have and idea of how you will work through future issues. No different than Windows in that way.