Integration with planned courses

I ride entirely outdoors, in a relatively hilly area, so sometimes it is difficult to do exactly the intervals given in the workout (I can’t push power on a twisty descent, or drop to total recovery pace on a steep section of a climb). I wonder if there could be a feature where you could upload your planned route (eg the one from Garmin that identifies climbs), and then the app could say something like aim for x watts on these climbs, y watts on the flatter sections, or something like that, using pbs on those climbs to estimate how long they will take.