As a hobbyist, shaders is up there as one of the most fun types of programming.. Low-level / relatively simple language, often tied to a satisfying visual result. Once it clicks, it's a cool paradigm to be working in, e.g. "I am coding from the perspective of a single pixel".

Ah yes, I dreamed about doing something like this, just with even more details ages ago, but concluded, I won't get even close to what I want, without having a big team at disposal and a supercomputer and/or a couple of universities collaborating interdisciplinary. But so far I was buisy with other things and reading about his experience unsurprisingly kind of confirms the challenge there is - mainly performance. But GPUs are on the rise and I am optimistic for the future. If the AI bubble bursts, I suppose lots of cheap GPU power will be avaiable for experiments like these and more elaborate ones. And if not, compute power/money will likely rise anyway.

I wish I had an intuitive understanding of how much I can do with a GPU. E.g. how many points can I move around? A simulation like this would be great for that.

The tectonics.js blog has some really incredible write-ups on how to do proper simulation of plate tectonics: https://davidson16807.github.io/tectonics.js/blog/news.html