To qualify for Google branding and to use the Android trademark and ship with the android marketplace a manufacturer has to comply with the "Compatibility Definition Document" - a platform spec document that includes some software behavior and a number of hardware features. including high speed wireless data, an X MP camera, a compass, acelerometer, touch, a standard screen res, etc.
The nook if memory serves lacks a camera at least so they didn't qualify.
Note that this doesn't say you get access to all google apps like navigation - it does appear another agreement is needed for those - I just don't know if that is a pay for access by the oem or some other arrangement.
I have no reason to believe otherwise, since some Android-based devices like the original Nook never use the name Android anywhere.
However, I could not find any income statement that details their revenue sources by channel/product line.