That's amazing. Mac Mini is very efficient and is a great little home server. Idles at 3-4w total for the entire machine. Plus, the M4 is a beast of a CPU. It might even be possible to serve a small LLM model like a 3b model on it over the internet.
It's a cool project. I might do it too. I have an M4 Mini sitting on my desk that I got for $550.