I've seen these types of tools a lot that all have the same pipeline: Use GenAI to create an image/find a source reference image -> use really basic algorithms to clean it up and align it to a grid + forcing a palette.

The output of this one does look good for the examples you provided, but I cannot see myself ever using it.

I don't really ever use these tools because they still can't stick to a single style for a game; Especially if you are using small enough sprite sizes like 16x16-32x32. Making one-off single frame assets is very simple and the itch.io assets page are flooded with them for free (AI generated and traditionally drawn).

I'd like to see one of these tools generate a pixel art spritesheet for a character with a walk cycle or other animations based on a character concept and a base character. It would be very impressive to have a tool that can do that consistently.