I’ve solved the issue with the following, if there is a more efficient method let me know!
<?php
$lists = get_field( 'testimonials' );
shuffle($lists);
if( $lists ){
$i=0;
foreach( $lists as $list ){
if( $list['site-wide_display'] && $i < 1){
echo $list['testimonial'];
echo $list['testimonial_name'];
$i +=1;
}
}
}
?>