After an update to Google Drive, I now have the 1x1 widget as well. But before I started this thread, I looked at the Google Drive app description in the Play Store and it specifically listed the 1x1 widget under "what's new", and the version number listed at the bottom of the description matched the version of the app installed on my device (I wanted to make sure I had the latest version before starting the thread). However, once the update became available to my device, the version number in the description changed.
I suspect that Google's staged rollout mechanism doesn't stage all aspects of an app update, and that in the midst of a staged rollout, the app, description, and "what's new" aren't always in sync. Staged rollouts suck even without this issue, but this makes it much worse.