Hi there :)

i'm currently working on an native Android app for my company and ran into some problems with Salesforce lately.

I hope i can find some help here.

What i want to achieve:
The company has a lot of Accounts in Salesforce with 3 important fields for the app: Name, Business (Workshop or Parts Dealer) and location(latitude, longitude)
I would like to show those Accounts(Workshops/Parts Dealers) as markers on a google map in my Android app based on a radius around the user's current location. So it would be more than sufficient to get the data as JSON or XML(i read about sObjects, which would be nice too)

The app will be freely available on Google Play Store and every user should be able to see all the Workshops/Parts dealers around the world.

The problem i'm facing is that i can't find a way to fetch the data inside my app without authenticating every user with a Salesforce-Login. 
Which API is the best to use in this case?

It would be so awsome if anybody could help me with this problem.

What i tried so far: 
- SalesforceMobileSDK: If i extend SalesForceApplication i always end up with the Salesforce-Login Screen.
It seems that every client has to be authenticated for API-calls to work. I tried using the method "peekUnauthenticatedRestClient", but this method only works on full path URL's(e.g. "https://api.spotify.com/v1/search?q=James%20Brown&type=artist"), which isn't really practically for my Use-case.

- I feel like i read nearly all docs about salesforce api, but can't quite get my head around how to solve this problem, although it seems like to be a pretty common use-case.  

- would a salesforce-apex method which would select all records inside a set radius around the user's location be accessable without authentication?

Thanks for your help in advance!

Roman