Android - How to get ETA from Google Maps App Inte

Question

I'm working on android app witch will navigate to a place and do some stuff based on the ETA.

I don't want to deal with navigation at all and this is why i use an Intent to open Google Maps App.

Is there any way i can run a service to get the ETA from Google Maps App?
Can i do it with Waze or any other navigation app?

If not,
what do you think about running a service wich will get ETA from Google Maps API every few minutes?

Thanks for you time.
Yirmi.