Do you link your phone to your car via Android Auto? That may be what’s keeping it alive?
Is your phone plugged into a charger? That may be what’s keeping it alive?
I know I don’t know. But those are potential differences between both your use cases.
I don’t use voice directions at all. But like you when my Android phone is both connected via BT/ WiFi to my car via Android Auto and is also charging via a mag Qi charger, the maps app never times out. It keeps sending images & data to the car’s display systems indefinitely.
I never use it any other way, so I don’t know which aspects of my setup affect the outcome how.
I’ll have to try again; it’s been a few years. My helmet bluetooth is supposed to arrive this morning, but it was shipped via Ontrac. It might be that the phone knows it’s in a pocket from the ambient light sensor and proximity sensor, so it sleeps maps after a few minutes. Sitting in a car mounted cradle, or even just dropped in a cup holder, it knows it’s not in a pocket.
Macs have a command line app called caffeinate which does exactly what I want. Perhaps unknowingly, you gave me the hint to search for that on my phone. Now I have a few similarly named Android apps I can look at. Most of them keep the screen awake, which is not what I want.
The map app is a battery hog on Android. Which incentivizes the phone to suspend.
Your problem may be as simple to solve as plugging the phone into a powerpack in the same jacket pocket. Once the phone thinks battery life is assured, the map app stays live. Maybe.
About all I know about iDevices is how to spell them.
I don’t use Android Auto, since my car doesn’t support it. And I very rarely plug the phone into a charger, because my phone mount is to the left of the steering wheel so a cable would get in the way. I do usually connect the phone to the car via Bluetooth, but I’m pretty sure I’ve used Maps with the phone not connected and it still stays alive and gives me voice directions.