It would probably be easier for her to simply look at the screen and open the iPad with her face. Assuming her iPad is eligible, you can find instructions to set it up here:
Use Face ID on your iPhone or iPad Pro - Apple Support
This is out of the box thinking but I have something else you may want to look into. My Dad had low vision problems. The Library of Congress has a special program for eligible people with low vision. They provided my Dad with the free listening device and access to recorded books. He happily listened to 2 books a week until the last week of his life. The device is designed for people with low vision and very easy to use. They would send my Dad a catalog and he was able to order what he wanted - for free. You may want to check it out. I’ve posted the link below. But your local library should also have details on this program. It’s pretty wonderful.
https://www.loc.gov/nls/thatallmayread/?cid=ar_by_google8&gclid=CjwKCAiA5sieBhBnEiwAR9oh2rRWKCUnnBtGNn2upMcJsuA5gF3td-20oEl64y3rvyG7DOSlnUM54hoC6eEQAvD_BwE