I looked around ArcGIS Runtime SDK for Android v100.1.0 but couldn't find anything on Geofencing. Is there any complete or partial support for Geofencing in Runtime SDK for Android?
There is support but it is a solution that would have to be built using the available resources in the documentation. It is not out of the box.
Here is a sample that uses 10.2.7 to create a geofence:
Using this as a rough guide, you can likely write a version that suites your needs for runtime 100.x
Hope this helps!