So, we have some very early potential patches for implementing groups with OAuth2:
https://github.com/puiterwijk/discourse/commit/1bd570e7ef9982dfb91becf371a056066f3cfc08
https://github.com/puiterwijk/discourse-oauth2-basic/commit/a9a6bcb15d17c48404d356e6b55d77628213538e
However since we’re using the hosted plan we don’t have a quick staging environment in which to test them, so they’re completely theoretical. Will try to get such an environment set up sometime soon but it is literally no one’s day job, so if it happens that anyone else could help review and test these that would be amazing.