Seeing as there is no difference in protocols between WiFi and Ethernet, anything visible in one should also work on the other. The CXN V2 is Roon tested so it should work OK via one of the alternative protocols. However it may present as a new endpoint and require activating.
In the Roon settings -> audio I see only two CXNv2 zones.
One via Chromecast Streaming under Roon tested and one via AirPlay under Other Network Devices.
That’s all, nothing with Ethernet…
Very annoying because the build in Chromecast only supports max 48 Khz in stead of the 96 it should be. A flaw in the CC implementation.