I am not a coach but I would definitely be interested; but ideally more for using on the SkiErg, as mentioned above (as it more closely replicates swim action in terms of cross training/improving swimming power/durability but on dry land).
I do subscribe to Ergzone but I cannot say that I am overly impressed personally as I do not use the coaching or community bits. As well as using it to execute the C2 WODs, I basically just created a personalised training plan via their web app which your app will more easily do (for those used to Intervals at least) plus extra features. I would happily swap my money/donate to an app that links better into Intervals for sure. And the W’ depletion sounds excellent. Similar to Xert & Athletica feature.
I have just started using RideCave which is also integrated to Intervals (& mentioned & on Intervals Forum) which replicates track racing (against personalised bots) as well as structured workouts & Plans It would be great if you were able to integrate something like this into your app; though perhaps the effort intermittancy might be more applicable to SkiErg I suppose than rowing. But younger rowers might also enjoy the competitive rowing races combined with recovery intervals & the chance to repeatedly try to win/improve on the next race lap. And it should fit well presumably with C2 BikeErg for racing.