Hi Fred - here’s an image of the adaptor board connected to one of the emonPi3 prototypes.
I don’t know enough about the HA integration side to comment too much on the data that’s available and how it’s parsed. For example, the emonPi3 will always output all the voltage and CT channels, even if they are inactive, as 0 is still a valid value. If the HA integration can filter out values that are known to be unused, that would be best - is that the first option you presented?