At the moment we can only use streaming services with Waze, rather than using our phone's built in media players to play music saved to our phone.

This is really impractical for long drives - I lose mobile signal all the time when I'm driving between towns and cities, and streaming services are no good for that
Also, streaming services are usually no good unless you pay for a premium version, otherwise you are constantly jarred by adverts
As it stands, I constantly have to touch my phone screen while driving, to switch between Waze and my local music player - this is really impractical and unsafe. Google Maps let's me integrate my local music player, it would be great if Waze did too :)