Decentraleyes is an excellent add-on that improves browsing speed and privacy with no negative side effects. Currently, the only font cached by Decentraleyes is Noto Sans. It also caches Google's Web Font Loader script and many major JavaScript frameworks.
Correction: Decentraleyes doesn't actually cache any fonts. Noto Sans is just used for the add-on interface. Font caching would make an interesting feature if the add-on developer is willing to implement it, especially if it bypasses fingerprinting.
https://decentraleyes.org
https://git.synz.io/Synzvato/decentraleyes
Web developers who are concerned about privacy exposure from Google Fonts can use google-webfonts-helper to extract the font files and self-host them.
https://google-webfonts-helper.herokuapp.com/fonts
https://github.com/majodev/google-webfonts-helper