This is a guide on burning the Android image onto the eMMC on the Banana Pi BPI-M3. The eMMC is 8GB and decently fast.
You will need to burn android onto MicroSD with Phoenix Card first and boot it. Then you need to enable USB debugging, install Google Composite ADB drivers, and write the image to eMMC with Phoenix Suit. Then you can take out the MicroSD card and boot M3 from eMMC.
Android Google Composite ADB Driver https://developer.android.com/sdk/win-usb.html