If you flashed with EZSP, you will need to use the zha component, not zigbee. I don’t believe the Xiaomi push buttons are supported yet, but you can check this thread, it’s fairly comprehensive.
Xiaomi support is in the works in the underlying zigpy/bellows libraries, so it may just be a matter of time. In fact, there is a fork of bellows that has Xiaomi support working today, but I don’t believe you can run that on hass.io.
For any other supported Zigbee devices, I believe you will need to factory reset them if they were joined to your SmartThings hub. After the reset, call the zha.permit service and go through the join procedure for that device. Check your log files for any errors.