So it turns out that Krea is naturally amazing at pixel art, and it just needs a little nudge to help it get to a consistent resolution. This is a set of pixel art loras intended to be run at exactly 1024x1024.

I created a custom node for post-processing:

https://github.com/envy-ai/ComfyUI-Krea2-Pixel-Art-Refiner

It just downscales the image to the specified resolution, palette-reduces it, and optionally upscales it back. Because the pixels are (almost) always a constant size, it doesn't try to do any guesswork about rows and columns. If you don't want to use this node, you can do the same thing in your favorite paint program.