My experience with easy debian was years ago, so bear with me if the following is not up-to-date.

The EasyDebian is a file which will get unzipped and mounted itself as a loopback device, and an application is kind of changerooting into that mount point. There is no separate device necessary for that, until you unpack the file to the device and mount this device always to the location, where the script of easy debian looks for the loopback file. This should be done via fstab entry.