Plugin shim to make Geo Mashup plugin work with the AMP plugin. See https://wordpress.org/support/topic/shortcodes-for-geo-mashup-not-working/

geo-mashup-amp-compat.php

<?php
/**
 * Plugin Name: Geo Mashup AMP Compat
 *
 * @package   Geo_Mashup_AMP_Compat
 * @author    Weston Ruter, Google
 * @license   GPL-2.0-or-later
 * @copyright 2019 Google Inc.
 *
 * @wordpress-plugin
 * Plugin Name: Geo Mashup AMP Compat
 * Description: Plugin shim to make Geo Mashup plugin work with the AMP plugin. See <a href="https://wordpress.org/support/topic/shortcodes-for-geo-mashup-not-working/">support topic</a>.
 * Plugin URI: https://gist.github.com/westonruter/c3d4d73418b310f12d3cba7245fccebc
 * Version: 0.2.0
 * Author: Weston Ruter, Google
 * Author URI: https://weston.ruter.net/
 * License: GNU General Public License v2 (or later)
 * License URI: http://www.gnu.org/licenses/gpl-2.0.html
 * Gist Plugin URI: https://gist.github.com/westonruter/c3d4d73418b310f12d3cba7245fccebc
 */

namespace Geo_Mashup_AMP_Compat;

add_filter( 'amp_is_enabled', __NAMESPACE__ . '\filter_amp_is_enabled' );
add_filter( 'the_content', __NAMESPACE__ . '\filter_content_to_fix_iframe', 100 );

/**
 * On standard mode sites, prevent the page in the Geo Mashup iframe from being served as AMP, since it requires JavaScript.
 *
 * @param bool $enabled Enabled.
 * @return bool Filtered enabled.
 */
function filter_amp_is_enabled( $enabled ) {
	if ( isset( $_GET['geo_mashup_content'] ) ) {
		$enabled = false;
	}
	return $enabled;
}

/**
 * Inject sandbox=allow-scripts attribute on Geo Mashup iframe and remove invalid name attribute.
 *
 * @param string $content Content.
 * @return string Filtered content.
 */
function filter_content_to_fix_iframe( $content ) {
	if ( function_exists( 'is_amp_endpoint' ) && is_amp_endpoint() ) {
		$content = preg_replace(
			'/(<div class="gm-map"[^>]+?><iframe)( name="gm-map-[^"]+?")/',
			'$1 sandbox="allow-scripts" ',
			$content
		);
	}
	return $content;
}

Installation instructions: https://gist.github.com/westonruter/6110fbc4bef0c4b8c021a112012f7e9c