Not sure if this is an iPhone thing or a Camry (2016) stock audio player thing but for a little while now, when I don’t have any audio playing on the car stereo (radio, USB, Bluetooth) and I’m using the GPS on my iPhone (16, though it did it with my 12 as well), the GPS will call in to give me the directions.
it used to just pipe into the stereo.
did something change on the stock Camry stereo?
here’s my current firmware (pic)

 

Try Toyotanation.com. They have section on audio and navigations systems.