Is there a way to integrate iHome iSS50 5-in-1 Smartmonitor with ST?
Unfortunately not at the present time. It only works with its own app or with HomeKit.
You could use an iHome plug as a “man in the middle” by having the ihome app turn on The plug when the sensor reaches a target value and then have that plug coming on trigger something in SmartThings. But it means dedicating a device just for that purpose so most people won’t want to do it. But if you did want to have a sensor value trigger the plug plus have some other things happen in SmartThings, it might be worth it.