Hi Shane
first thing you could do is place a bit of text on the screen bound to the property of the geodatabase that says whether it is valid or not - that will help you know when you fire up on android/ios devices whether it's finding the geodatabase or not.
re defining paths, I ended up using AppFramework.userHomeFolder.path as the base under which seems to work. Not sure if there is a better practice or alternatives - if anyone knows then would be good to find out.
The test for windows is optional, just means you can place it where you want on a pc...
property string apppath: Qt.platform.os === "windows" ? "c:/examplefolder" : AppFramework.userHomeFolder.path;
property string gdbpath: apppath + "/gdb"
etc...