I used something called Osmand~ on my android phone (the squiggle is important, for some idiot reason there are multiple versions of the thing) -
It comes from here.
It is free, you can pre-download whole states at a time onto your phone. Decent enough maps, and does turn by turn driving directions, all you need is a car charger for your phone.
There is a version on the play store, but it costs money (they are both the same thing with all the features, just this one is a slightly different build that is free).
It isn't as good as copilot in terms of the clever stuff like lane guidance, but American road layouts are so simple that it isn't a problem. The maps themselves seemed fine everywhere I was.