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.
This is the first time I'm exploring this, but I think you're wrong.
On Mastodon you can:
So post visibility is not something you set per profile, but per post. But you have an effective tool to decide who you let in AND remove on the way.