A new version with Google support and fix for the conflicts will be released soon.
I have tested the fix with my Wordpress extension. If someone can test the confilict fix with other oauth extensions it's welcome! This is the PR FriendsOfFlarum/oauth#12
If you would like to try it out you can run
composer require fof/oauth:dev-cw-fix-route-conflict.
You can go back to the main version with
composer require fof/oauth later.