I know how browsers work, but thanks.
The tool you linked does not solve the same problem, as the problems isn’t file types but URIs. Google is able to provide the tiniest possibly font files by hinting them for the specific browser/platform requesting them. We never consistently or predictably know the resultant URI of a Google Fonts-hosted font file. Here is a Tweet to the same effect from two days ago. Believe me, I’ve researched this :(
https://twitter.com/csswizardry/status/1265716520346320903