Organic Maps (available on F-Droid and the Play store) is the closest FOSS alternative to Google maps i have been able to find. Routes are not perfect (they work but could be better) and time estimations are best-guess as it is completely offline minus map downloads, but its a great alternative and also has killer hiking trail data that beats Google’s by a country mile. The offline bit also means that it works without a data connection, and for the privacy-conscious it’s a major boon.