Since I have not created a plugin using OAuth or OAuth2 I will not try to hallucinate an answer.
However this should be of value to you.
shane.isbell created
Plugin Store Manifest and Spec Files now in Github
which contains copies of actual manifest and OAS (Open API specification) files and as we know is where the use of OAuth2 would be indicated.
Using GitHub search for OAuth2 results is some hits.
Notice that one of the hits is a manifest and the other is a OAS (Open API specification) but that they are not from the same plugin.