Smartthings needs to present multi component devices in a way that allows voice assistants to independently control each switch of a two gang or three gang switch.
There are lots of examples of these devices.
Zooz zen30 fan/light switch (zwave)
Aeotec Nano dimmer, which allows separate functions for S1 and S2.(Zwave)
Tuya Smart Zigbee 3.0 2 gang switch
(this is the one with an integration in the smartthings app, again, separate functions for S1 and S2)
And lots of others. Like the recently added Heltun Quinto, which has 5 outputs, not just multiple inputs.
These are multi endpoint devices. There are multiple different ways of implementing that, but they are part of the standard protocol for both Z wave and Zigbee. And smartThings should be able to handle them, both in its own automations and in exposure to voice assistants and Ifttt.
Submitted with respect.