I would love to be able to support this. I have a stryd myself but I do not have and do not have access to a treadmill. So, I’ve not been able to get to Breakaway to also support Smart Treadmills.
Do you have a Smart Treadmill?
As you’ve stated, Stryd calc power based on flat surfaces and the power will change based on incline. If I know how this is being calculated, then I possibly can implement this as well. (Note: BreakAway already supports sending SLOPE (incline) based bike workouts to Smart Bike Trainers using Intervals.icu workout builder)