Many thanks @keno.mario-ghae. It appears that the CA-8210 provides IEEE 802.4.15 PHY and MAC support functions with the higher levels of 6LoWPAN, Thread, Zigbee being supported by the host system. Does this mean that the CA-8210 would use the same firmware for all of them?
Some other devices (eg. USB-KW41Z) appear to use different firmware loaded onto the device to support some of the higher levels of specific protocols.
OpenThread looks like a good base for an open source implementation of Thread. I'm not aware of any similar open source implementations of ZigBee 3.0. It may be that license problems make this difficult ...
It might also be feasible to use wireshark/tshark on the Ci40 with the CA-8210 as an IEEE 802.4.15 packet sniffer.
I have recently had a Liberty 100 electricity smart meter installed (with a gas smart meter due to be installed when parts are available). It came with a distinctly underwhelming monochrome Pipit 500 in-home display (IHD). Communication is by ZigBee and I am curious to know if I can capture anything interesting from them. I would expect them to have some cryptographic security!
I would be interested to hear from anyone else who has tried tinkering in similar areas.