The following the work around for SmartLife deviced that do not have a SmartThings integration:
In the SmartLife or Tuya apps create separate “tap-to-run” on and off automations (scenes) for each device you want to use in SmartThings.
In SmartThings run the Tuya integration. Do NOT use the SmartLife integration. The difference between the SmartLife and Tuya integrations is that the Tuya integration doesn’t end with an error message. And when you look on linked services the imported scenes are listed under Tuya, unlike SmartLife which is blank.
When you go back to the main page in SmartThings you will find on and off switches for each device at the very bottom of the page in the “No Room Assigned” section.
They will probably say they are off line, ignore that for now.
Create a virtual switch in SmartThings for each SmartLife device. This can be done using “create a device in the IDE” or using SmartThings Labs (3 dots in upper right corner of SmartApps) in the mobile app.
Using SmartThings automations create 2 automations. One will say toggle the “on” scene when the virtual switch is turned “on”. The second will say toggle the “off” scene when the virtual switch is turned “off”.
Or use a WebCore piston for each device. The first part of the piston say toggle the “on” scene when the virtual switch is turned “on”. The second part of the piston say toggle the “off” scene when the virtual switch is turned “off”.
Reportedly Sharptools can also be used, but I have never tried it.
I have been using this method for months with no issues.