I've been thinking about the exactly the same thing. And I've been trying to train some AI model to do this job. Turns out it's really hard. Last year I tried, it was a total failure because the AI models' capability was too weak.

I tried again this year with exactly the same way to train the model, it's much better. Actually much better than I expected. I'm not sure if it's ready for professional game development.

This is what I've got so far: https://www.godmodeai.cloud/ai-sprite-generator, looking forward to feedbacks.