[smallerfish]

It depends on why you want to de-google. Running Android means that you're plugged into their ad-analytics data collection. Firmware layers are extremely unlikely to be reporting personalized analytics into that engine.

On the other hand if you're trying to avoid an oppressive state, you probably want to avoid any potential for a sub-poena to a big corp yielding information on you; in which case considering fully open firmware makes much more sense.