What "login with" options currently work?

[awesomerobot (Kris)]

Apple login does require payment

Discourse Apple Authentication

Just as a note: I tried to set this up and you need to pay a annual fee in my case around 125 USD per year! [Uden titel]

you can alternatively support it through Discourse ID

Discourse Apple Authentication

For a free option, you can also configure your site to use Discourse ID, which includes Apple as one of the login options.