Update: Unfortunately, having used Apple Maps’ offline maps for a few weeks now, I’ve realized that they too “expire” maps after some time. I think 2 weeks. That means any maps you downloaded become inaccessible and you have to re-download them all, every 2 weeks. And the worst thing is they don’t even warn you about it until it happens. I withdraw my recommendation for Apple Maps.
There is an open source Android version of OSMand Maps on F-droid that is 100% free
https://www.f-droid.org/packages/net.osmand.plus/
Update: Unfortunately, having used Apple Maps’ offline maps for a few weeks now, I’ve realized that they too “expire” maps after some time. I think 2 weeks. That means any maps you downloaded become inaccessible and you have to re-download them all, every 2 weeks. And the worst thing is they don’t even warn you about it until it happens. I withdraw my recommendation for Apple Maps.