The problem is that without 3.5mm jack, there is no antenna for FM. Phones used the headphone cord as the antenna. I doubt it is possible to repurpose the USB-C wires as antenna. If it was, would require a custom USB-C chip.

I couldn't find FM/AM USB-C dongle. My guess is that nobody uses FM/AM or if they do, they get a standalone radio.

My biggest use for the FM radio on my old phone was sporting events which have the commentators broadcast locally with no delay.

Now I have to remember to bring a little pocket one or be sure the old phone is charged whenever I go to sporting events. Really kind of a pain. Luckily the kids also like to play games on the old phone so its a handy distraction machine on the train ride.

The phone wouldn’t be doing much in that case I guess… the dongle would have to bring along the headphone jack as well, so you could listen to it! I guess the phone would be the battery, and maybe a speaker I guess.