Seems there is a new way to interact with loop devices, in particular private loop devices via mounting loopfs to some location. From a quick glance it looks like you can have different locations for loop-control and loop* devices other than /dev. Maybe this is what android is doing under the hood? We might need a more generic approach then the swapping out the LOOP_PREFIX depending on the target.

https://lwn.net/Articles/819625/