Hi,
I struggled too, but it it possible.
for OAuth2, you need to set up Google Cloud,
[Comment connecter toutes les google apps a n8n en 5mn]
and there is also an alternative with Google Service Accounts described below:
FInd YouTube for Tech Tim and video ’Self-Host Your Own Automation Platform with n8n + Docker’
at timetamp 18:40
All the best!