CarPlay
While you’ve been able to use Google Maps with CarPlay for a couple of years now, this was only available in the full-screen view; the CarPlay Dashboard was still limited to Apple Maps.
As expected, iOS 13.4 opens this up to letting third-party mapping apps play nicely with the CarPlay Dashboard as well, although developers will still need to update their apps in order to provide the necessary views to support this.
In addition, the CarPlay Dashboard will also show information on any calls that you have in progress.