Disclaimer: Bluetooth novice question ahead. I'm not trying to troll you with inaccurate / improper use of terms :D
I'm working with a Bluetooth device that communicates using the WIDCOMM stack. In Android, I see that communication is done using RFCOMM sockets and, so I assume, the RFCOMM stack. How would I allow an Android application using the RFCOMM stack to receive data from a device using the WIDCOMM stack?
It doesn't matter what stack the remote device is using. You are misunderstanding what widcomm is. RFCOMM is a standard protocol service that is implemented by all common Bluetooth stack implementations (including widcomm, bluez, android, etc.). widcomm is just a particular implementation of the stack. different stacks can communicate because they speak the same standard RFCOMM protocol.