oAuth2 and 2fa how to combine?

I am trying to get the oAuth2 plugin to call the 2fa process once the oAuth2 login has been accepted, in the same way that the standard login process does.

Being new to using GRAV I am not having much success (Though I did manage to get the LinkedIn oAuth2 to work eventually, the supplied plugin code being incomplete/out of date).

Any hints on where to go?