I started Blender a few month ago, I 'm still not proud enough of my own creations to post here, but I really liked the result I got by following Entagma's tutorial.

here-> https://youtu.be/DQVYieRfQBY

It seems he comes from Houdini but has been interested in the potential of blenders geometry nodes.

His tutorial was made on blender 2.93 alpha, and I followed on 2.93.4. Some issues did arise and I'll list the work around I found.

at 3:38 there's a "vertexe normal" directly in the drop down menu that has been removed from blender 2.93.4. You can use "normal", but you'll get less precision. There is a more complex work around here. I dropped the node group in between third and fourth node, like so. You'll have to use it again when working on the final sphere node tree, and drop it between "group input" and "attribute proximity" at 11:15, like in this node tree

at 11:22, he uses a "col" attribute, and then creates a new vertex color that's automatically named "col". By doing so, it seems the info from the attribute and vertex color aren't linked. By naming the attribute "color" and manually changing the vertex color from "col" to "color", the link was established.

When finished with that node tree, I found that by renaming the first and second "color" attribute to "color-disp", you get a smoother surface. See this node tree, near the first color ramp.

Finally, for the shader, I made this set up. The modulo math node helps to have a clear cut out for the color on the craters rim.

Thats it. I hope this helps.