Hi there, @EstherKlein9 ...
I may have some good news for you, but it would depend on if your school has purchased the Respondus 4.0 software which allows you to load multiple questions from a file into the Respondus software and then import those questions into a Learning Management System such as Canvas. As a former Canvas administrator, I create many quizzes for our instructors, and I used the Respondus 4.0 software we purchased to create text files (formatted a certain way) that contained many questions so that I could essentially batch upload them into Canvas without creating questions in the Canvas interface one-by-one. I even wrote a blog posting here in the Community about the process:
Batch Uploading Quiz Questions with Respondus
To answer your question, though... Respondus does allow you to format a CSV file, and then you can upload your questions that way. So, while it doesn't accept a *.xlsx file, you could convert that to a *.csv file, make sure it is formatted correctly, and then load it into Respondus so that you could get those questions into your Canvas course. I've not tried the *.csv file option myself...as I've always preferred the *.txt or *.rtf version because it was much easier for me to create than the *.csv file (I recall seeing examples of the *.csv format, and it kinda hurt my brain, to be honest). Here is a website with more information for you:
Respondus 4.0 - Respondus (check out the two videos under the heading "See How Respondus 4.0 Works" ... "Creating Questions" and "Importing Questions")
Also, all of the above pertains to current Classic Quizzes in Canvas. But, there is also this help page on the Respondus website that pertains to Canvas New Quizzes:
Publishing to Instructure Canvas "New Quizzes" – Respondus Support
I know this might not be a direct answer to your question, but I wanted to share this information with you ... so that you know there is additional software you can get to make life a bit easier for importing lots of questions into you Canvas course(s). This might be something you want to share with your school's Canvas administrators...in case they would be interested in investigating this product.
Hope this helps. Take care, and be well.