While this used to be true, the two-way integration was quietly pushed out for all customers with the V2 version of the app. You will never see to harmony smart apps. Harmony connect, and “Logitech Harmony triggers”.
So now you get some really nice integration, although you do have to do some set up work to make it work.
Many of us are using Amazon echo to control harmony activities by voice now. This is done by having smartthings trigger harmony activities. For example, I can say “Alexa, turn on Netflix” and the echo will tell smart things to turn on a virtual switch which then triggers a harmony activity. Very cool.
You don’t get full control of harmony, and some of it’s a little wonky. For example if you want to be able to make the volume go up you have to have two separate harmony activities and keep switching back-and-forth between them.
But you do get a lot of control. For those of us who want to use voice (I’m quadriparetic) it’s especially nice.
But you can definitely have a SmartThings routine start the TV or some other harmony – controlled device.