I just logged into the website to order some more NanoPC-T3 boards and I find that they are no longer available.

I've just design and made a number of expensive boards to use with this board. The new T3(2GB) is a completely different footprint.

Is the T2 compatible with the same Android build as for the T3?

It sure looks like basing any designs around FriendlyArm boards is not a good idea as they just disappear without any warnings. :(