Frequent Flyer is an app from the same people that made the Panel App. If you have an account on the Panel App, they won’t let you set one up on the Frequent Flyer app, so make a new account with a different email address if you want both.
It is very similar in that you are rewarded points for allowing it to track location and other data, fill out periodic surveys, and run in the background. The difference is what the rewards are. This app focuses on travel rewards, literally Frequent Flyer miles through airlines (Alaskan Airlines, Southwest Airlines, etc.). You can also redeem for gift cards to the airlines or to Hotels.com, Marriott, Hilton, and even AirBnB!
They also offer sweepstakes for chances to win the above listed rewards as prizes!