You might find it interesting that there's an entire genre of youtube video that's designed to just be chucked one by one into slideshows for elementary school teachers to use as their lesson plan. Including videos that are just "2 minute timer for kids!"

e.g. https://www.youtube.com/@Ask.the.Teacher

"Independent Reading: Count Up Timer for Classrooms": https://www.youtube.com/watch?v=AfLfJtVeME8 straight up just stock imagery and a timer lol