What I’m trying to achieve is a simple frontend form to provide access to a restricted client’s area like described here:
Restricting access to your site
But instead of using default email/password login, the new passwordless authentification should be triggered.
I know the docs already cover the required techniques …
… but a recipe with all the individual steps to make it work on frontend would be just great. I think the new authentication method is particularly well suited for such a purpose, so other people might find it useful, too.