I'm renting a brand-new car, a 2018 High'N'Dry, that has a USB style
port that allows me to play a flashdrive through the radio -- but will
not charge the phone using the same port. Isn't that very unusual?
Impossible?

It also does not have an AUX port. Isn't that very, very unusual for a
car radio that has a "Media" button and which plays from a USB style
port? If they go to the trouble to put in the USB circuit and jack,
how much more trouble is it to put in the AUX circuit and jack. Don't
the chips have both to begin with, because it's cheaper to make only one
chip than a different one for each model?

But the point of my post is:

1) There is no adapter made which will change a 2.5mm stereo plug into
a USB connector, right??

2) I found this:
https://yourthingstore.com/products/...er-car-charger
but it has what seems to me to be the strangest disclaimer:

"With total contact conductive electrode, the product has the
compatibility to the usage of most cars' cigarette lighter.
All kinds of Nissan, KIA and Subaru car are not included. Besides, Honda
(Odyssey/CITY/Vezel/Crider/FIT/XR-V), Toyota(Vios), New Citroen, New
Jetta, Peugeot(201/301/2008) are also not applicable.
You can check the internal structures of cigarette lighters to confirm
if it is applicable or not."

What about the internal structures of the cigarette lighter could
possibly cause this to not work if it works in other cars? Isn't it a
straight 12 volts? Do they have the polarity reversed on some** cars?
Hard to believe but what else is there?

Aha! The physical shape! Is that it? It looks like it is of
unremarkable shape.

**Especially hard to believe on some Toyotas but not others, some Hondas
but not others, etc. Though it's good to see that this will
apparently work on all American cars.

I ask not because this one item is so important but maybe this one is
just more diligent about putting the warning