Send a link to a popup and use that link in the popup as a button

send_link_to_popup.php

<?php // Ignore this first line when copying to your child theme's functions.php file.
/**
 * Based on https://youtu.be/zml-xz78o2Q
 */
function send_link_to_popup() { ?>
 	<script type="text/javascript">
		jQuery(document).ready(function ($) {
			const popupID = 1728, // Change to your popup IDs.
        		sel = '#my-button'; // Change to your button's CSS selector. Can also be '#my-button > a' if needed.

    			$(document).on('pumBeforeOpen', `#pum-${popupID}`, function () {
        			const trigger = $.fn.popmake.last_open_trigger[0].firstChild, // Grab the popup trigger's link element.
					link = trigger.href, // Grab the href attribute from the trigger.
          				btnLink = $(sel); // Grab the button in the popup.
				
				// If the link has something, inject it into the button's link.
      				if (link && "" !== link) {
					btnLink.attr('href', link);
      				} // if
      			}); // listener
			
    		}); // jQuery
 	</script>
<?php }
add_action( 'wp_footer', 'send_link_to_popup', 500 ); // Load the script in the footer with a "late" priority.
/**
 * You can add the PHP code snippet to your child theme's functions.php file
 * or with third-party plugins such as My Custom Functions and Code Snippets.
 *
 * Learn more:
 * - https://docs.wppopupmaker.com/article/84-getting-started-with-custom-js
 * - https://docs.wppopupmaker.com/article/552-getting-started-with-custom-php
 */