I’m mostly on board with this, but even with using only trusted, vetted… apps (which is already a huge challenge for some) I wouldn’t go for sure that none of those are going rouge (as we saw before: some adv company buying a decent SW and making it a bloatware).
Getting back to my first point: I just had a situation where I had to install Viber for example, and I can’t stress enough how grateful I was for the Storage and Contact scopes features.
I’m not familiar with such solutions, but I wouldn’t get your hopes high, as Google Docs is not a collection of publicly available files (like YouTube), rather files closed behind different accesses.
Based on this, depending on how a file is shared with you, you could be asked to authenticate yourself somehow. Without the deeper understanding of your situation, I can only think of one solution: downloading these files with manipulating the links, like this for example (if they are public): https://stackoverflow.com/questions/9045392/getting-the-download-link-for-a-public-google-docs-file?rq=1
If they are not public, I think you still have the chance to do this, but I can’t see any steps around authenticating with Google in their own site. And then download the file.