I have a bunch of Smartplugs. I didn't have any Scenes, so I just made one in Kasa and had the Echo look for new devices. It wasn't found. However, it appears you could make a group in the Echo app to do the same thing? All I have is on/off, I'm not sure how that would work with dimming, but it should, it works with my Osram Smartbulbs. You could make a Scene in Kasa and then make a Group in Echo and name them the same name.