Yes, there are apps that will work on phones that may show if you have been near people who have been or are COVID positive. There are several concerns with these apps.
The apps will be dependent on development of a national database of people that have tested positive for COVID and them allowing that information to be put on their phone and them and you having Bluetooth networking turned on (what most of time people use in cars to connect phone to a hands-free device). Questions that arise are 1. Will the information be true, some people see people putting in their phone that they are positive to scare people, the issue of a person being cured, will they be removed from the database (notice how little is reported on the number cured), 2. Will people use the Bluetooth connection to hack in and make your phone appear you are positive, and 3. Will government use to follow people in the app, apparently in China that has been a fear as they are running this type app and early this year 23 million cell phones ceased use there raising question if people trashed or turned off phones.
Some other countries than the USA have implemented some type of these apps.
We are still learning whether they have been helpful, used or how accurate. How close will phone determine is exposure range is a question.
Apple and Google are working on an app to do this to work on both Android and iPhones. Apple actually already has a product and has it in the beta copy of the new release of their iOS (beta copy is when public can get to try but they are still finding major bugs in it and company has not done regular the release of the app or program).
If you did not want to be notified if anyone had been near you (how much later it will tell you to protect their privacy is a question) the best two things would be not install the app, but when new iOS comes out for iPhones you may not have a choice, and 2 have Bluetooth turned off except when you are actually using it. Normally I only turn Bluetooth on in my phone when I will be doing a long drive so I can receive calls. I keep off at other times so others cannot connect to my phone and two if my hands free device is on in my car and I am near it I have problem of I cannot hear caller as they are being broadcast in my car.
The app shows some promise as a possible way to track on COVID infections and warn people to be tested, but it also raises privacy issues and people’s rights to project medical information.