CNN did an "advertorial" about this gadget, I have one that is similar that I use on an old iPod. I'm surprised airlines would allow something like this that is transmitting a signal during flight, but they probably can't enforce. Unless the pilot notices his instruments are going wacky and makes an announcement (as they apparently did back in the day when too many people were listening to a playoff game on transistor radios)
https://www.cnn.com/cnn-underscored/reviews/airfly-duo-bluetooth-adapter-review