Great initiative! As someone who has worked on Auth systems multiple times, I can so much relate to it. In fact, at one of the jobs I created something quite generic (SSO by SSO, multiple token types, multiple interfaces (including OAuth), multiple password backends, email domain specific verification methods, etc. Wanted to open source it, but then given it was related to security and we were not really a security company, we let go of that plan.

All the best to you and your team!