Earlier quoted context omitted.
As mentioned in the post there's a _free_ API for non-commercial use that I maintain, and you can make commercial use of it by becoming a GitHub Sponsor: http://github.com/sponsors/protomaps But being "Google Maps compatible" will never be possible as long as the Google Maps client library and data are proprietary.
That's awesome, just saw that myself! This is a super cool project. Fwiw with "Google Maps compatible" I didn't mean showing Google's Maps, I was thinking more a drop-in replacement to (some subset of) Google's client library.
Most open source efforts have consolidated around MapLibre GL https://maplibre.org which is a maintained fork of Mapbox GL before their switch to a source-available license.