All I had to do was add SmartThings in the Harmony app and that created the Logitech Harmony Connect app and the Harmony Hub devices in SmartThings automatically. After that was done, I added instances of the Logitech Harmony Hub Control app to power off my TVs when everyone leaves.
I originally had Harmony controlling some physical devices in SmartThings, but I wanted to be able to do different things during the day vs. night, so I am now using Harmony to flip a virtual switch in SmartThings. I use that virtual switch as a trigger to do different things based on the current SmartThings mode.
The Harmony Connect app doesn’t poll the hubs automatically because the hub device types don’t have the polling capability. This means that it won’t automatically show the current activity without hitting refresh. I am using Pollster to automatically refresh the current activity for me. I don’t use the current activity as a trigger for anything in SmartThings, but it’s nice to see the activity log which shows when the TV was turned on and off.
Honestly, while my integration is working, it is very disappointing that you can only control activities via the integration. I would much rather have the ability to send any command to any device without affecting the current activity.