I'm the Meridian team's technical writer.
In regards to Xamarin, the Meridian Android SDK doesn't currently support Xamarin.
Regarding the API question, there isn't an endpoint that does what you're asking, but you can do this programmatically using the SDK as described here:
http://docs.meridianapps.com/developers/sdk_guide_android#loading-directions
Thanks for your questions! If you have any more, I'm happy to answer them.
Cheers,
Shawn