https://wordpress.org/support/topic/how-to-enable-shortcodes-oembed-for-comments-in-amp-pages/

embeds-in-comments.php

<?php
/**
 * Plugin Name: Embeds in Comments with AMP Support
 * Plugin URI: https://gist.github.com/westonruter/3cf877833a8f94776536e3f90bb30ea2
 * Author Name: Weston Ruter
 * Author URI: https://weston.ruter.net/
 */

namespace Embeds_In_Comments;

/**
 * Force balanced tags with support for AMP custom elements.
 *
 * The `force_balance_tags` function is not aware of custom elements (which contain hyphens),
 * so this strips the first hyphen before doing force_balance_tags() and restores it after.
 * Note that this does not yet support AMP tags that have multiple hyphens.
 *
 * @see force_balance_tags()
 *
 * @param string $content Content.
 * @return string Content.
 */
function force_balance_tags( $content ) {
	$content = preg_replace( ':<(/?)amp-:', '<$1amp', $content );
	$content = \force_balance_tags( $content );
	return preg_replace( ':<(/?)amp(?!-):', '<$1amp-', $content );
}
remove_filter( 'comment_text', 'force_balance_tags', 25 );
add_filter( 'comment_text', __NAMESPACE__ . '\force_balance_tags', 25 );

/**
 * Add embeds to comments.
 *
 * Props sheabunge.
 *
 * @link https://gist.github.com/sheabunge/6018753
 *
 * @param string $comment_text Comment text.
 * @return string Comment text.
 */
function add_embeds_to_comment_text( $comment_text ) {

	/** @global \WP_Embed $wp_embed */
	global $wp_embed;

	/* Automatic discovery would be a security risk, safety first */
	add_filter( 'embed_oembed_discover', '__return_false', 999 );

	$comment_text = $wp_embed->run_shortcode( $comment_text );
	$comment_text = $wp_embed->autoembed( $comment_text );

	/* ...but don't break your posts if you use it */
	remove_filter( 'embed_oembed_discover', '__return_false', 999 );

	return $comment_text;
}
add_filter( 'comment_text', __NAMESPACE__ . '\add_embeds_to_comment_text', 8 );