Using Google Drive API to edit other user's files

I am building an app that functions as a markdown editor, and have Google authentication / login functioning. I have users asking if they can choose to have their documents save to their google drive rather than to my servers, which seems to work fine via the Google Drive v3 API, saved to the app data folder.

However, users are also able to generate a collaborator link for others to visit and which allows them to edit the files as co-owners. I would like to maintain this sharing capability with the Google Drive files, but this (very old) answer suggests that sharing in this way may not possible with files in appdata, because:

Appdata content is supposed to be exclusive to the application.

Does this mean that, as long as my users all access these files exclusively via the app, sharing appdata between users is possible? Or is the appdata folder exclusive to the application and the user? If so, is it at least possible to share editor access to google drive files created by my app but outside the appdata folder?

I'm imagining this process:

1. User1 creates a file in my app and then my app saves it to his Google Drive (preferably in appdata)
2. User1 generates a collaborator link via my app, gives it to User2
3. User2 visits the link which opens User1's file within my app, edits it
4. User2's edits are saved, and my app updates the original User1's file via the API

Question:

"Or is the appdata folder exclusive to the application and the user?"

Answer:

Yes, it is exclusive for your app on their Drive.

Notes:

• Use the AppData folder for Application Data, not User Data.
• If the file is created by your app, and you want to store it in the user's Drive, you can use the https://www.googleapis.com/auth/drive.file scope. You app will always have access to that file because it was created by it.
• Keep in mind that if your app requires restricted scopes you will have to go through verification.