While this article digital signature is the issue, but if you create your own apk file and install in your phone, or any one do the same, with out using Play Store at all what is the difference if you create your own deb package and install in your system or any other use it at his own risk, with out use any Debian official repository?
In order to fulfill LGPL, you should provide a way for your users to download object files and by themselves links and package it with their own version of GLib.