Hi David,
I'm sorry, my misunderstanding. I thought do you want to design the gateway IoT with an Ethernet MCU.
Is this possible to achieve ? and is there any example or application note supporting this?
What are the challenges and considerations I would need?
You can add another Zigbee product. As you know, the ZigBee protocol is a standard and all the products should be compatibles, that is the reason for Zigbee Alliance.
Also, you have to be sure that the stack is compatible, for example,
The JN-AN-1189 is a simple demonstration from ZigBee Home Automation Profile Specification version 1.2.2, so, the external device has to be compatible this version and the stack that you are working on(ZHA, ZLL, ZB3...).
Hope it helps.
Regards,
Mario