I think it might be useful to use Bluetooth connectivity (and a “companion app”) to allow the user to stream audio on FM frequencies (87.5 to 108.0 MHz). i know that in many states it is illegal to broadcast without a license, but it should be considered as an idea for an external module to be attached to the gpio.
I hope that this idea can be taken into consideration at least by the diy community, I am attaching the photo of an fm module for arduino:
61tB18DnOcL.AC_SX425|425x389
forgive me for my english (google transalated), thanks for reading and stay safe out here!