Those are Wi-Fi switches. Wi-Fi does not have a standardized home automation communication protocol the way that zigbee and zwave do. So each manufacturer just makes up their own commands.
Consequently, unless a Wi-Fi device is on the official “works with SmartThings“ list, smartthings probably won’t understand it.
Sometimes there are workarounds. See the following FAQ:
FAQ: WIFI Devices in ST? How can I integrate a WiFi or Bluetooth device that isn’t on the official compatibility list?
In this specific case, Meross does have an IFTTT channel, so you may be able to get partial integration with that. But only partial integration. If you look at their IFTTT channel, you will see that you can turn one of the switches on as the “that” but there is nothing for the switches on the “if” side.
That means that if you turn the meross switch On and off at the wall, or with its own app, or with echo, smartthings will not know about it. This is a common issue with Wi-Fi switches.
I don’t know if that affects your decision to keep them or not, but it is something to be aware of.
In the future, for full compatibility, always check the official “works with SmartThings list“ before buying any Wi-Fi devices.