The Pico will not be visible to SmartThings through the official integration, so I’m not sure if it will do what you want. You would have to also have a lutron master switch and then that’s the only switch that the pico could work with. So it might be OK as an auxiliary switch in a three-way, but it’s not just a dimmer switch on its own.
There are a number of battery operated switches that might be of interest. The FAQ covers both battery operated and mains powered buttons and switches:
One popular one is a Z wave device, the Cooper 9575, which looks exactly like a regular switch and does communicate to the SmartThings hub.
But there are a lot of other options as well, just see the FAQ.