From there, you can reply directly by voice or typing, and your response will be sent from within the app the message was received, marking it as "read" in the process.
While some manufacturers, such as Samsung, have attempted to shun the Google Assistant in favour of their own virtual helper, many Android devices can harness the former by default out of the box. The function works even if there are multiple unread messages. It will tell you the contents of the message, the app it came from, and the sender. So just check when you say "read your messages" and see if your Google Assistant will read from other messaging apps. With this feature, you can either dictate or type out replies, although you'll need to grant the Google app notification access for this to work.
Google Assistant has long had the option to read one's SMS messages aloud, but that has not done much good if one's conversations resided in third-party apps.
Once the permission is granted, a card with the text message pops up, and the Assistant starts reading it.
Voice assistants are constantly getting new talents added to their repertoire by the companies that develop them in the hope that they will dominant the field and reach ubiquity ahead of their rivals. For this, you would have to give Google app notification access. In case of an audio, video, or an image, the Assistant will simply say that "the message contains an audio/video/ or a photo", and won't play the media for you.
According to Android Police's source, Google Assistant will finally expand its skills to other messaging platforms, too. Don't expect lesser-known services and apps to be supported yet though but maybe someday Google will provide a public API that all developers can use. Notably, the read-aloud feature could be useful when users are driving, cooking or otherwise have their hands full. However, we are not sure whether the new feature is updated from server-side, or we have to install it.