Nielson data is a very small very targeted piece of data. Nielson may be able to somewhat tell something about your family (so critically it is about a group of people instead of an individual person, which is a major difference).

Considering how most people use their phones, this basically gives Google all of your information. There is little to nothing they would not know about you. Worse is them being able to get information about other people (thanks to them messaging you, while you have this tracker running) without their consent.