In your case I’d just use the “denoise (bilateral filter)” module and adjust the sliders to the point where you are comfortable with the result, possibly set the blend mode to color and adjust the opacity to let just a little bit of noise through to make it look a bit more natural.
If you want more control you could use the wavelet mode of denoise profiled.
At least from my experience non local means is not that well suited to deal with smooth surfaces as it ‘tries to find structure’ within the image. If there is nothing there it just makes things up. 