In the Android mobile app, there’s a reference to attachments at the top of the task:
If you click the attachments link, you get each attachment on a separate slide. Photos have thumbnails, but Google Docs look like this:
If you click the “thumbnail,” you get an intermediate Google page that you have to click again to go to the Google Doc. Basically, instead of being a “smart URL” it’s handled like a generic URL.
The attachments all appear again at the bottom as comments, and if you tap there they open in Google Docs with smart URLs:
So the feature request is to recognize Google Docs (and I guess Dropbox and Box) in the mobile attachment slides, since they are officially supported types of attachments.