Well to partially answer my own question...
Finding myself with an afternoon off work on a sunny day I called around and got a booking for a 90 minute "foiling experience" lesson on an eFoil, which I finished about an hour ago. I think the eFoil board will be a valid introduction to foiling as it was a good grounding on getting up & staying up as well as foil trim.
It highlighted so issues for me (I can't backhand turn, no matter what I tried

). I also had more success driving upwind into maybe an 8 knot wind and small chop than I did downwind. Crosswind wasn't very successful for me either.
I think with a sail or wing I might have had better directional stability just due to me being used to them and giving something to pull against. This may also be a plus with towing behind a boat, that feeling of a pressure to pull against.
Good news is my session on the eFoil has only increased my desire to get into some sort of foil sailing in the near future!