If you covered your face, altered your apparent build, had no technology, spend used cash, you'll be fine if you want not to be tracked.
Facial recognition is so good now all the security cameras can know where you are. Mobile phones track all your activities and location. Digital money is tracked.
Your privacy comes really from being a harmless nobody not worth the bother.
Google in the case of Android is giving you a free OS and free apps which cost them a lot of money to know all about you, your intentions aspirations and what you might buy next. You see this if you look over shoulder of someone else, what they are being shown differs if a feedback loop.
The concern about hacking is similar to official access just different motivations.