Accurately measuring running zones on hilly terrain

Hi, I really love this app.

My only problem is that my runs on hilly terrain (where I live, it’s mostly hilly) do not really capture whether I stuck to my zones. In the app it measures zones based on pace only, and so I usually get very low scores for my running workouts, even though I stuck to the right grade adjusted pace (I know this just a Strava thing) and heart rate zones.

Would it be possible to measure the zones instead based on heart rate? I feel that at least in my circumstance this would capture my workouts more accurately.

Thanks a lot for your great work!