Happy Pixel Day!
First impression is that I really like the complexity of your dithering throughout the picture, especially on the radial gradient around the outside.
I love that you wrote code to assist with the drawing, as you’ve got some great structures (and dithering!) that is ridiculously tricky otherwise. That looping border and it’s shading is really well formed. I hope you push further with coding+illustrations, as the output is really refreshing and good quality.
Oh, and the frog’s sweet!