TIL there's a 12v socket in the passenger footwell
 

RTFM and all that, the Owner's Manual mentions an outlet under the glovebox, without a diagram indicating where.

Here'a a picture if you're curious, and if you're OCD you'll immediately notice the cover writing is upside down.

Not sure how eager I'd be to put something in that socket. Seems like a prime location for a passenger to kick it and break whatever might be stuck in it. My wife has broken more USB chargers than I care to count anymore. No doubt her 'passenger braking action' would almost immediately wreck anything plugged in there...

There are 12V outlets all over the dang vehicle. I think I've counted 6? If you want to run a radar in my wife's Lexus RX, you have to stretch the cord to the glove box outlet.

That's actually a popular use for this outlet: I've seen a few forum threads where posters use the footwell outlet to run a radar cord from the headliner, down the A-pillar, and over to the outlet. Easier than hardwiring, I guess.

I suppose it depends on the model, I've only found five in my '17 958.

armrest
console
under glovebox (only one)
bottom of rear console
left side of rear cargo area

As for hard wiring, if you don't need to use a specific adapter it's probably simpler/cheaper to use an in-line 12v-USB adapter. Like one of these:

http://amzn.to/2gG26FS

There are other variants, with plugs on the ends, single sockets, combinations, etc. I've got the one above providing power to a dashcam (line running up A-pillar) and a passenger-side cord for phone charging. I really hate having cables snaking all over the console or have sockets RIGHT WHERE THEY'LL GET KICKED. Thus I prefer not to use the existing sockets.

2011 turbo with 4 zone HVAC has two outlets on the rear of the console. Everyone in the vehicle has at least 1, even a dog in the rear compartment.

On closer inspection, the panel under the glove box has openings for two sockets, but only one is installed. Not that I'd need/want a second outlet down there. Looks like they 'cost managed' the second one out.