In Canvas, I have an assignment that requires students to upload a file. In it, I restricted file upload types because some students keep submitting HEIC files. So, I specified jpg,png,pdf in the file upload restrictions. Now, a student is trying to upload a PDF file from Google Drive and it won't let her. She is able to find the file in the Canvas Google Drive upload tab and she can select it, but when she presses upload/submit, she gets an error message. And because she's on a school chromebook, it won't let her download the PDF from Google Drive to the chromebook.
This seems like a bug to me. If you allow PDFs to be uploaded, they should be allowed to be uploaded from Google Drive.