Whenever you look for an alternative to some Android app (or an Android app per se), my app listings can serve well. In this case it is: Navigation. But as on SR we don't just drop links to search engines or lists, I'll of course name some examples I feel recommendable for your case.
The first two are based on OpenStreetMap (OSM). You've mentioned badly maintained user-contributed material with Google Maps. OSM lives from user contributions as well, but here the maintainers are humans so the results are usually way better.
I personally use OsmAnd, more precisely the version freely available at F-Droid (I stopped using Google PlayStore entirely some years ago). It works quite reliably, even with navigation – be it by car¹, on a bike or per pedes. There are plenty of additions, plug-ins and maps available. The concept is to work offline, so all material is downloaded to the device – which works quite granular (though it might be a bit tricky at times to find out what piece is missing on a route). Overall I'm quite satsified with OsmAnd.
- offline navigation (incl. night mode)
- public transport
- trip recording
- POIs, WikiVoyage, Wikipedia integration and more
- cycling, hiking, driving…
- huge collection of addons and other material, e.g. listed at IzzyOnDroid
OsmAnd: Routing, navigation, downloads (click images for larger variants)
My second recommendation is OrganicMaps – again from F-Droid. This is a fork of the app RockpaperLizard recommended, Maps.Me, which was made when the original MapsWithMe was sold and was undergoing massive changes not really welcomed by the community. I have not used this app myself, but heard it recommended many times as being easier to handle than OsmAnd while not having all its features, so I tend to think of it as "simplified OsmAnd". Routing etc. is said to work great with this one, too.
OrganicMaps: Routing, navigation (here in night mode; larger pictures again on click)
Being available at F-Droid means, as for OsmAnd, the app is open source and covered by a free/libre license. Both authors of course welcome donations, so should you decide for one and be happy with it, consider a "material thank-you" :)
And if you want to help and contribute to OpenStreetMap, you can find some apps here supporting you with that: add missing POIs, improve descriptions and more. All your contributions will go through a review, which should help avoiding the problem you outlined.
Off the record (as it's not FOSS), I'll also mention Locus Maps – which I used happily for years when I still had a Google account. I also contributed to this app which, like OsmAnd, is quite modular. It allows to select between many map sources, has a lot of add-ons and material available (find some listed here at my website again). While quite bound to Google, the author still has an eye for privacy, which shows e.g. in the fact he separated addressbook access from the main app into a separate addon, so it's your decision how much you trust him. Locus even supports importing your own KMZ files, so you can have your own travel guides including images and all, completely self-contained (OsmAnd only offers GPX for this). And it works entirely offline as you wish, but can also be used with online maps – so no gaps on routing where you have to figure the missing piece. There's a paid version available as well, offering the full range of features. Unfortunately, both of them come with trackers (I don't know when this started), including Facebook, so for me the app lost its "privacy seal".
¹ I only miss here are traffic information and re-route recommendations on jams – but I'm sure even that is possible if you know how