FWIW: Most of the Tecsun radios will tune the 87.7 frequency since they're manufactured in China, and the Japanese FM band runs from 76-90 MHz. There's also been discussion in the past about the FCC extending the FM band in the US down to 76 MHz to relieve congestion in the commercial portion of the FM band in the larger metropolitan areas. Who knows, with the former analog TV channel 6 now vacant, Uncle Charlie may eventually expand the FM band just like they expanded the AM broadcast band in the early 1990's. Of course, that all depends on whether the FCC decides the needs of the consumer are more important than enriching Washington's coffers with another spectrum auction.
Radios being able to tune down to 87.7 (or technically 87.75) dates back to the days of analog radios. TV stations on channel 6 used to advertise that as a feature, particularly with their news shows. They would point out you could listen to the news on your car radio on your way home from work. That largely went away with the move of full power stations to digital, though WPVI in Philly tried to keep it going after the digital transition. They switched to digital for the main broadcast but shoehorned in an analog audio carrier on 87.75 for that very reason. The FCC told them to knock it off so they had to stop.
Speaking of who's using channel 6...it's true that no full power stations in the US are running in analog on 6, but there are many stations who are currently licensed on 6. Most are LPTV/translators (some analog, some digital) but a few are full power digital stations like the previously mentioned WPVI. A check of the FCC website shows 91 licensed stations on channel 6 today and that number is likely to do up as stations move from UHF to VHF with the upcoming repack. It's possible the FCC could set aside that spectrum for FM, but I wouldn't count on it. TV stations are probably already on edge with all the spectrum they're losing and there just doesn't seem to be that much support for an increased FM band.