Organic Maps is the best open source Maps App I've ever tried
It's essentially an open source fork of maps.me by the original creators.
I've been using OSMAnd for years, but it always felt laggy and not that reliable. Searching was slow and so on. Many street or things it didn't instantly find.
In the Graphene App Store I jnust discovered Accrescent (another app store thing but only with like 10 apps - they're all gold though, god damn)
An in there I found organic maps. And this shit is google maps level responsive. If you're on the lookout for a google maps replacement - consider trying this.