From you issues:
Quote:Need to determine what packages to include in final release.
Password hasher
Any Security packages
Emailer
Should also determine if these packages should be included in the UserAuth namespace or within their own namespace in the CodeIgniter application.
This is partially why there's never been an official CI authentication. You haven't even got started yet, and I could already start wondering why you would do this or that, and if I really want this or that.
Password hasher? What's wrong with PHP's native password functions?
Emailer? Wouldn't CI4 have its own?
Your long term goals ... is all stuff that is very app specific, and likely to bloat that authentication, or at best clutter it up.
Requires MySQL ... surely a good percentage will bitch about that.
"It will have basic templates for controllers and views that for users to start from" ... Probably the biggest mistake in your planning so far. It'd be better to just have good documentation, otherwise you end up having a bunch of people that think your example is their app.
"To eventually become the CI4 standard for user authentication" ... If there's going to be a CI4 standard, then why wouldn't CI4 just have it built in? There are reasons. Look them up.
I don't want to discourage you, but rather hope that you don't make mistakes thinking that what you want is even remotely ideal. You should definitely carry on with your project, and plan to spend 100s of hours on it. It happened to me. Great learning experience. I started my authentication project about 10 years ago. I thought that people would be excited, and that there would be a community that wanted it, and would want to help with it. Heck, I even named my authentication "Community" Auth. My advice is, plan to do most of the work on your own, or you might be disappointed.