Most non-tech savy people aren’t even looking for an alternative map app. They are just going to use the one that comes pre packaged on their phone.
I don’t know how many people found it through the Play Store, but for a point of comparison, OSMand has over 10 million downloads. That’s 10 million people who are interested enough to seek out and install it, despite not being tech savvy enough to get it from F-Droid, etc.