I haven't tested MagicEarth, but never have I spent as much time miserably lost as when I spent a very determined month trying to use OSMAnd+ (the main AOSP OSM client, at least as far as I knew at the time?).

It's dreadful at driving directions, and it's not like I live somewhere weird. It was getting me lost even in a town with a 30k+ student state university.

MagicEarth is based on OSM and their navigation is great, both for driving and walking (haven't tried cycling). I even got better routes suggested when driving vs Google Maps (I compared with a friend using GMaps, he switched to MagicEarth after that :-) ). The only time it messed up was by suggesting a non-existent walking path down a hill in Kiev, which resulted in me rolling down and slicing my arm open, nothing to serious though. Overall I'm happy enough with it to not spend more time looking for other alternatives. If anyone has a better alternative, I'm always listening.

I'm not sure openstreetmaps has a good driving experience?

I've been using Magic Earth for several years, its getting better and better.

Its closed source, but privacy orientated apparently.

and has anyone inspected what they both do on Wireshark etc?