I've charged phone, Kindle, CO2 meter from both the front and rear USB A ports, and they seemed to charge quickly enough.
It's quite annoying to me to realise that my old Golf did have this capability, in a single port, but I didn't realise it was there. It shared an output/input with the iPod player, having a strange connector I'd never seen before that was supplied with two interchangeable leads, one with the iPod connector and the other with a USB A socket. I used the iPod connector when I got the car, and didn't quite twig that if I unplugged it and plugged in the USB lead, I could have charged my phone. After some years the iPod became corrupted and wouldn't play. Muggins just started carrying CDs in the car and using the integral CD player. Didn't even pull out the iPod, which I discovered when I gave up the car could be restored by the computer and the music files reloaded. So there I was, no iPod and no USB socket, all because I didn't open up the arm-rest and take a good look at what was inside it. (In 2009 when I got the car I didn't have an armful of USB-charging devices, like I have now, so I didn't spot the potential. I thought what was in the arm-rest was just a music player.)