Ideally, it would be great to add Google Drive as a storage account, much like we currently can for Box, Dropbox, OneDrive, and SharePoint Site.
FYI, there are other PDF read/annotate solutions that do this (some even offer collation features). I would prefer to use a solution from Adobe, whom I trust, but I can only do that if you actually have a decently workable solution.
Hi wsvoems, jesse9goodman,
Acrobat Reader for iPhone and iPad supports Google Drive via Apple's Document Picker now.
To add Google Drive as a storage option
- Install the Google Drive app on your iPhone/iPad.
- Launch the Google Drive app and sign in.
- Launch Acrobat Reader.
- Open the Location Chooser by tapping the blue text in the top bar.

- Tap "More Locations..."

- Tap More.

- Enable Google Drive.
- Tap Done.

- Tap Google Drive.

Now you can open the documents stored on Google Drive in Acrobat Reader.
Hope this helps.