So, I want to be able to input Nav destinations and use the phone while someone else is driving. I found this:
https://www.coastaletech.com/DELUXE_LOCKPICK.htm
but don't think it is worth $229. I did basically the same defeat to my prius (which has the same generation Nav as my GX) by cutting two purple wires (speed signal) between the navigation head unit and the computer and inserting a DPDT switch. Anyone know where the nav computer is on the GX and how to get the trim pieces off to get to the back of the HU?

 

Found this linked to this forum, which does what I want:
With the Navi on
tap Menu
tap Volume
tap upper left of the display once
tap lower left of the display once
tap upper left of the display once
tap lower left of the display once
a menu of options should appear, press and hold the Override option until you hear a beep then let go
hit the address button and you should be able to enter the address while driving

This only works until you turn off the Navi so next time you're on the road you must do it again...only takes seconds to do and works great.

Also, the purple wire with the red stripe going to the nav computer under the passengers seat is the one to install the switch on for more permanent immediate override while moving. A simple SPST will work fine instead of having to use a DPDT like on the Prius. I guess I just needed to search more.