The key to using SmartThings with Harmony isn’t in the buttons on the handheld remote. It’s in the Harmony concept of “activities.” An activity doesn’t have to be mapped to any of the physical buttons, so you can have a lot of them.
An activity can combine entertainment devices and home automation devices, so a single button press (or activation by a SmartThings timer or motion sensor or even voice command via Echo) could do something like “movie night”
Turn TV room lights off except for one Hue hulb blinking orange to indicate the movie is about to start
Dim kitchen lights to 50%
Start Roku and turn to Netflix
So That’s the activity.
What would start it?
You could have any of the following trigger a Harmony activity:
Use a voice command if you have Echo integrated with SmartThings (“Alexa, turn on movie night”)
Toggle a button in the SmartThings mobile app
Tap a widget button on your phone or smartwatch
Walk past a motion sensor but only on Saturday night between 6:45 pm and 7:00 pm
Reach a specific time (30 minutes after sunset), but only if a specific person is home
Hit a button on the minimote
Unlock the front door if a specific person is arriving
So basically by itself Logitech Harmony can do fixed schedule timers or buttons on the remote or taps on activity choices in their phone app.
Adding SmartThings lets you extend that two ways. Now you can have a Harmony activity also start/stop devices controlled by SmartThings. And you can use SmartThings events, which are much more complex than Harmony time schedules, to initiate Harmony activities.
Did that help?
I use mine mostly for voice control of my A/V components, but that’s just what’s most valuable for me. Of course that also requires having an Echo integrated with SmartThings.