I have decided that in lieu of developing a custom app - which is overkill - managing the devices will, at launch, consist only of going to specific URLs to trigger specific routines on the connected devices.
For example: going to (URL) with a specific authentication will cause all units to reset, or go into low-power-shutdown, etc.
This functionality is baked in to the Spark Core cloud. Spark's Reference Documentation
There isn't any need for the management interface to do much more for basic functionality, so that will be all that is needed for now.
Essentially, it takes any kind of mobile app development out of scope but still allows any mobile device (or computer) to trigger important functions.