kmap
Builds Garmin maps from OpenStreetMap
...Every feature is optional: leave out what your device does not need, and the map gets smaller and faster.
Two styles are built in, modelled on OpenStreetMap and OpenTopoMap, and kmap can reuse the look of a map you own where its licence allows. Profiles keep a separate set of build settings for each device.
kmap runs as a full-screen terminal interface, and every feature is also available from the command line. Map data comes from Geofabrik's OpenStreetMap extracts, updated daily; the tools kmap needs are downloaded on first run.