Is it possible to have my web app allow users to upload images and store the uploaded images in a Google Drive or Box account? Not the user’s Google Drive or Box account, but one that is owned by the web app.
If that is possible, any pointer on how to go about it would be appreciated.
Yes, this is entirely possible using the Google Drive SDK. Your app can create an application-owned account with which your app will be able to upload and download files using the API as normal.
You can of course use a regular account for this, but then you will need to manually authorize at least once to store the token.
(no idea about Box)