Sorry. If you use the latitude and longitude from the LocationSensor, reverse geocoding is easy. If the latitude and longitude come from an outside source (as you are getting from your raspberry) , your options are as indicated in the link.
I would use javascript using Google’s Maps Javascript API . Get an API Key from Google. This service is not free., although Google does provide a certain amount of ‘credit’ as described in the link. The technique uses Google’s database to provide the address. Be aware that an address is not available for every geocoordinate pair. Coordinates in the middle of a cattle field will probably respond with ‘No address available’
All the options I am aware of are mentioned in the Reverse Geocode link posted earlier. What you want to accomplish is not easy, it requires advance coding skills Try some blocks by creating a basic app that takes a latitude and longitude from text and use the Google api, post what you tried and someone might provide specific advice.