wrapping the link in a passowordless email in a button
I have managed to get the passwordless email to work. The link it contains is one ugly, 3 lines of a link. Can I somehow hide this this in an html button? Do I use freemarker and if so, where? In the Applications/authorized redirect URI input box? or directly in the customizations/email templates screen?
You need to create FreeMarker email template. Be aware that due to limitations of various email clients, designing of HTML email template is actually as frustrating as web development in the era of Internet Explorer 8. responsive-html-email-template stands as a pretty good starting point for such task. The repository readme file tells you what to consider when creating such a template.
I usually use Stripo templates. They integrated AMP technology in their builder. And it's all for free.