Hello, thanks. I went to gamalytic.com and searched Subnautica, and they have "Gross revenue (base game): $126.1m ($90.9m - $161.3m)" and I tested the extension just now and it reports "~$ 135 M", so about $10M more than Gamalytic., which seems like a fair result?

PS the source is open, so please feel free to suggest refinements to the algorithm :)
https://github.com/opyate/steam-revenue-calculator-firefox-extension