This topic does not constitute legal advice. Attention should also be paid to the licences. These could change. Please refer to the complete licences for all details.
We assume no liability for the correctness, up-to-dateness and completeness of the linked pages and no liability for possible legal consequences. In case of doubt, your trusted lawyer will always be able to answer your questions with legal certainty.
Google Webfonts Helper - Free tool written under MIT licence:
google-webfonts-helper
A Hassle-Free Way to Self-Host Google Fonts by Mario Ranftl
https://gwfh.mranftl.com/fonts
Open Source Font Attribution (authors, licences and more) Google Fonts: An informative overview
https://fonts.google.com/attribution
Preview Google Fonts, - Glyphs, About and Licence: An informative overview
https://fonts.google.com/?preview.text_type=custom
Licences:
SIL Open Font Licence (OFL)
https://openfontlicense.org/
https://en.wikipedia.org/wiki/SIL_Open_Font_License
Apache License
https://www.apache.org/licenses/LICENSE-2.0
https://en.wikipedia.org/wiki/Apache_License
Ubuntu font licence
https://ubuntu.com/legal/font-licence
https://design.ubuntu.com/font
Information on the licences can be also found at developers.google.com:
https://developers.google.com/fonts/faq?hl=en