Have you tried the auto pause feature? That should pause your ride when you stop and restart it when you move again.
I searched for auto pause before this post since I’ve never used that feature on any head unit but fellow riders do. However, if you’re not savvy to it, it’s worth searching for that yourself to see the results for your head unit since they’re not great. However, maybe it’s working fine now; most complaints are older.
I thought average power already had an accurate power for moving time, though. I don’t think it’s adding a 0W every second you’re stopped.
Have a gander at this: Why does average power calculate differently between services?
If you edit out coasting, that’s a cheat code we’d all like to have, please share if you find it.