List pages by custom field?

Function wp_list_pages() accepts arguments from get_pages() function. To list pages filtered by custom field use meta_key and meta_value in parameters array. A list of accepted parameters can be found here and here.

wp_list_pages([
    'meta_key' => 'your_meta_KEY',
    'meta_value' => 'searched_value', // optional
]);

meta_value is not mandatory, if you skip it, a list of pages with any value of the custom field will be returned.