LocusMap is a perfect app to use for navigation, plus it can store maps offline as well, it has a free version as wel, thus, the usecase is strong. This blog details the process of downoaod and configuring local maps to your device.
Note You need to register with LocusMap server to use this option.
Click on menu and goto “Maps”
Select “On-line” option
Select “OSM-Other” option , the list will expand with more options, we are interested in “OpenTopoMap”.
Click the submenu (the tree vertical dots) for “OpenTopoMap” and select “Download”
Now you need to select an area to download, you can download a country level map (will take alot of time), select area (best option), or this screen (also the best option)
Let’s select “This screen”, this will bring one tiled map (based on your screen bounding box(Bbox)).
Now select select “Select area” option to download maps of selected area.
Note Also check OSM app called OSMAnd.