What country are you in? The device selection does vary significantly.
There are a couple of battery operated devices that look very much like switches and that work with smartthings and that are easy to wall mount, but again which ones are available depend on the specific country you live in.
There are also some “smart battery covers“ which are devices which fit over a wall switch so that you can leave the power always on to the bulbs while having a button or switch device to turn on and off. But again, country matters.
And there are even a few devices which can be wired in to replace an existing wall switch but don’t cut the power to the bulbs.
Why don’t you start by taking a look at the following FAQ?