If you still have access to Classic Quizzes, there is a piece of software called the Respondus 4.0 Exam Authoring Tool that can be purchased to batch upload multiple quiz questions into a Canvas course all at one time. I've got a blog about it here in the Community called: Batch Uploading Quiz Questions with Respondus - Instructure Community (canvaslms.com). I no longer am at the Technical College, so I don't have access to the software any more. You could use this software to load the questions into a Canvas course, and then you could migrate your questions over to a New Quiz.
I also found a support page on the Respondus website that might be helpful: