Totally get why you built one to meet your needs, but any thoughts on opening the app up? That is where the gap in the market is. I have a Water Rower, so I won't be buying your hardware (sorry), but if you open the app up I would be interested to try. I understand some of your workouts won't work without the resistance control, but there is a market out there for a good app. Since you already have one, might be a reasonable thing to look at. Although if all of the workouts need the resistance, than that could be a non started.
Looks super cool though. And I wish you luck. If I were in the market for a rower, and not already have one mostly collecting dust, it would be something I would definitely look hard at.