It is possible to sign up with username/password, but not with the built-in forms. You will have to create a custom form for that.
Hint for a sign-up - the signup action will complain that “email already exists”. I’ve managed to find workaround by adding the same input field value to user’s email field as well.
Just created the Proof-of-Concept in my experimental app - seems to work fine.
For the reference:
Talking about completely anonymous apps, that’s a different story. In brief, there is no session storage, so either you have to “invent” your own sessions storage mechanism, or create non-personalizable app, or utilise built-in user’s mechanism.
See the thread here: