Yeah, the problem is that Training defaults to strength training afaik, which is sets based.
So I don't think so. Maybe stick with generic?
Even when I record native cardio activities for personal use, I always get useless fields like avg speed and elevation gain which aren't applicable.
You could try SPORT_TRAINING + SUB_SPORT_CARDIO_TRAINING, which gives me the following 3 main metrics: Calories, Time and Avg Heart Rate. Speed and elevation gain are there, but at least there's no distance.
(* I'm assuming SPORT_TRAINING + SUB_SPORT_CARDIO_TRAINING = "native cardio activity", as I only tested the latter.)
What's displayed in GC is based on the sport/subsport. Maybe you have to look for a different sport/subsport. What's displayed based on that isn't something you can change in your app.
