Lots of community members doing this one of three ways:
use the Harmony universal remote (usually the Harmony Home Hub version, but others as well). There is a new version of this integration currently in beta, reportedly working well, should be in wide release soon. This lets you turn the tv on/off, but you only get channel control from the harmony remote itself.
I’m using the older version of this integration and like it a lot. I can press an activity button on the harmony remote and have the TV come on and the lights go down. Or toggle lights from a remote button. But again, not full TV control from ST. I really like the Harmony as a universal remote, though, so I’m happy.
use a WiFi to IR blaster (usually the Global Cache iTach) with the RoomieRemote app. RR provides an official ST app. Requires a yearly fee.
use a WiFi to IR blaster (again usually iTach) with a home built controller. Many variations on this.
See the topic linked in the previous post for discussion of all 3 options or search the forum for iTach for more discussion.
The ZXT120 works by self identifying as a zwave thermostat, so it only accepts thermostat commands. I don’t know anyone using it for A/V equipment control, the iTach gives you a lot more flexibility for a similar price.
Some community members have used the zxt120 for air conditioner control, but the integration has been somewhat challenging. For more on it specifically, see:
Danny is a good friend
He wrote this integration back when he was working at SmartThings and then when the forum was updated it got lost so I re posted in Hackster hoping that developers can still use it.
I have it working on 2 different projects at home where I control lights with an Apple TV remote for example.