Not using Google Maps is difficult, but it can be done. I'm currently using OsmAnd from F-Droid and it works awesome. I would recommend it to anyone trying to live without Google services.
It's not difficult to use Apple Maps on an iPhone. You make it sound like Google are the only realistic maps provider available.
It is such a chore to look something up in OsmAnd that makes me throw all the privacy awareness away and go immediately to Google Maps.
So while replacing Google Maps can be done indeed, it is not a pleasant experience to replace it with open source solutions.
There's also OpenStreetMap.org.