More information from the manufacturer of the US model, Illumra.
They believe the switch might work with smartthings once smartthings has zigbee 3.0 support, But they haven’t received any reports yet one way or the other. The new V3 hub does now have Zigbee 3.0 support. The other hubs do not as yet.
However: the Illumra switches can only be set to one of four different Zigbee channels, and you have to manually switch between them if you aren’t using a hue bridge.
If ZigBee 3.0 support is available, the Click for Hue can be configured to transmit on 1 of 4 ZigBee channels by holding one of the buttons for >10 seconds. Button to channel mapping is:
.
Button 1 : lower left (BO) - ZigBee Channel 11
Button 2: lower right (AO) - ZigBee Channel 15
Button 3: upper right (AI) - ZigBee Channel 20
Button 4: upper left (BI) - ZigBee Channel 25
So if your smartthings hub is on a different zigbee channel, you’re going to be out of luck.
I would go into the IDE and see what zigbee channel your hub is using before ordering these.