The reason the FastHTML bare-bones from-scratch auth example is bare-bones is to show you the minimal pieces that need to be built if you want to do auth from scratch. That doesn't meaning doing it from scratch is a good idea -- it's shown for folks that have the need for something fully custom.
Just want to say thanks for introducing me to HTMX. I know a bit of react, but as a more backend/data focused person HTMX seems better way to go and have way less breaking changes as these frontend frameworks are constantly changing the way they manage state and everything I've written has to be rewritten every few years. It's an awesome idea to just serve html where there aren't constant breaking changes.
I think most projects have very bare-bones examples. I just need to be able to find a course on udemy with a fully production ready example with things like managed databases where a service is doing backups of the db and I don't lose data, auth pathways for creating users, updating passwords, and code that securely segregates things by user, scalable, deployment and sanitizes queries to protect against injection attacks to get an idea of how someone else would do it and have the confidence that I'm not building something that is easily hacked.
I think FastHTML will quickly get there, because it's built on starlette and gunicorn that many production systems already use, but I'm coming from react and I'm not super familiar with these.
The docs walk you through how to use OAuth, which is probably a better idea for most folks, especially for beginners: https://docs.fastht.ml/explains/oauth.html
(I'm the founder of the FastHTML project.)