Came here to say Cooper, Eaton and Hubbel all make plates like this that cover imperfections and also align the switches better. My old hose and TP-Link switches sometimes reset because the faceplate rubbed the bottom rest under the paddle. These solutions fixed all that, and the look is cleaner... YMMV
Here's another option
I bought these Eaton ones off Amazon:
https://www.amazon.com/gp/product/B000OESAFY/
https://www.amazon.com/gp/product/B000KA19MS
They're ok. The only issue I have with them are that due to the extra plastic around the Kasa switches compared to a regular switch, it makes the cover stick out a bit rather than sit flush against the wall.
It's something I could live with because it looked better than the existing cover plate, but isn't as nice as the single gang cover by Kasa. If you have OCD, you may not be ok with it.