Above Magento, email does still not support the use of web font, you can have an more specific explanation on
While web fonts don’t have universal support, here are the email
clients where they are supported:
Samsung Mail (Android 8.0)
The browser downloads all CSS resources, regardless of the media attribute. Check your network tab on your site and you'll notice even on mobile devices it downloads styles-l.css.
The media attribute allows the user agent to pick the best adapted one for the device it runs on, in other words it will de-prioritise styles-l.css which helps prevent it from ...