I can highly recommend OSMAnd, also available on F-Droid. It is not intendet to use it as an Android-“MapService” but as a nearly to perfect offline-navigation stand-alone programm (esp. for hiking and biking, quite OK for car).
For a real service maybe you can check Unified NLP for GAPPS-free devices (which I never tried and only hardly know how to use…)
And why do “Strava” need Google-Services? For the GPS signal? Or only to install it (then you can download the APK by the well working java-programm raccoon at a PC).