I've definitely seen use of src:local(...) in the CSS served by Google Fonts in the past, but they may have changed things, or perhaps it depends on details of the request, the detected browser, etc. YMMV.
When you select fonts on Google Fonts, the website instructs you to link to CSS hosted by Google, which is simple to implement, but not performant. Really, you would want to load that CSS asynchronously, so that the rendering of the whole website doesn't wait for Google Fonts. (Here's how you load CSS asynchronously, by the way: https://stackoverflow.com/q/32759272/247696 ) Or even better, host the fonts yourself.