In response to the FCC asking Apple to "do the right thing" and enable the FM radio in the iPhone, Apple have responded to say they can't because the iPhone 7 and iPhone 8 don't have FM radio hardware.
https://www.notebookcheck.net/Apple-tells-the-FCC-they-can-t-enable-FM-radio-in-the-iPhone-8-because-it-doesn-t-have-one.253320.0.html