I know this hasbeen discussed in the past, but I’m tired today and I don’t remember exactly where.
Anyway, there are a couple of different ways to do it. The main point is that SmartThings can request that harmony activities be turned on. So rather than having harmony turn on the smart power outlet, you want to have smartthings turn on the smart power outlet and then turn on the harmony activities. You can do this with a delay in between in case you need to wait for the power to turn on, which is pretty common. In that case you can either daisy chain it or use web core. (I’ll let other people explain those details if you need them)
And once you have a way of doing it from the SmartThings side, you can just set up a virtual switch to start that process and then you would have echo turn on that virtual switch.
This is the same way that we have echo start a routine or change a mode. So here’s the FAQ for that approach.
So again the idea is to set up a sequence in SmartThings where first the power outlet comes on and then shortly afterwards SmartThings Requests the harmony activity that does all the regular harmony stuff. And you trigger that sequence by a virtual switch coming on. That way you can have echo turn on that virtual switch and everything will happen.
Sorry I can’t give you more details, but I’m sure other people will be glad to fill-in if that’s not enough to get you started. 