I use BRouter for offline bicycle navigation.
BRouter is open source navigation software built on OpenStreetMap, intended primarily for bicycle routing. It offers both web and Android versions. The Android version calculates routes as GPX tracks, which are then fed into a mapping application. My preferred OpenStreetMap application, OsmAnd, supports BRouter as its navigation back-end. OsmAnd allows me to configure the frequency, repetition and units of instructions. I use Ivona TTS with the UK voice, which I think sounds more natural than either the Ivona US voice or Google’s TTS offerings. In sum, this gives me accurate, offline navigation, tuned to my method of travel, anywhere on the planet, with superior maps to traditional commercial offerings.
Carry a towel and don’t panic.