HomeKit works great with hue, but smartthings only works with HomeKit if you set up a separate server and then use a hue bridge emulator to fool Homekit into thinking your smartthings devices are hue devices attached to that bridge. So you can bring your smartthings devices into HomeKit but you can’t bring your other HomeKit devices back into smartthings. And it requires quite a bit of technical skill to set up.
Still, there are lots of people who do it. If you’d like to talk to them about the process, see the following thread: