Posted Sep 11, 2013 8:15 UTC (Wed) by glaesera (subscriber, #91429)
Parent article: Firefox OS on the ZTE Open
Android is non-free it is open-source, but it is a non-free proprietary product.
See here: https://fsfe.org/campaigns/android/android.html
Also it is highly recommended, to not use the default app-store, but this instead: https://f-droid.org/
Some free clone of Firefox-OS like Cyanogenmod should not be necessary at all, because this is free and open software by itself.