Is there any way of getting a thumbnail of a file that is inside a shared folder?
The 'get_thumbnail' function can not be used with shared folders right? Is there any other way? I'm using PHP.
If you only have acces to the file/folder via a shared link, then you are correct, it is not possible to use the get_thumbnail endpoint with a shared link URL to generate a thumbnail. Nor is there an alternative way to generate a thumbnail.
A feature request already exists to include a preview/thumbnail URL for a shared_link, I have added your additional vote for this feature to that request.