How to generate expiring URL of the page?

This plugin fits most of the requirements that you need:

https://wordpress.org/plugins/public-post-preview/

It allows you to share a preview of the page to anyone with the link.

You can modify the expiry time with a filter.

add_filter( 'ppp_nonce_life', 'my_nonce_life' );
function my_nonce_life() {
    return 60 * 60 * 24 * 1; // 1 day
}