acf-relationship-field-shortcode.php

<?php
/**
 * Output an ACF post relationship field type using a shortcode:
 * [ca_acf_relationship_field field="field_name"]
 * You can also pass `post_id` as an attribute
 *
 * Works with Post Object and Relationship fields, when the return
 * format is both post object and post ID
 *
 * This code assumes you are copying this into functions.php of
 * your child theme.
**/

// Setup the shortcode
add_shortcode( 'ca_acf_relationship_field', 'ca_get_relationship_field' ); 

function ca_get_relationship_field( $atts ) {
	ob_start();
	
	global $post;
	$defaults = array(
		'post_id' => $post->ID, // Default to the current Post ID.
		'field'   => '',
	);
	
	$args = wp_parse_args( $atts, $defaults );
	
	$related_posts = get_field( $args['field'], $args['post_id'] );

	// Check if we have a single post (post object, post ID) or an
	// array of posts then convert to array.
	if( is_object( $related_posts ) ) {
		$related_posts = array( $related_posts );
	} else if ( is_scalar( $related_posts ) ) {
		$related_posts = array( $related_posts );
	}
	if ( $related_posts ) {
		?>
		<ul>
		<?php foreach( $related_posts as $related_post ) {
			if ( is_scalar( $related_post ) ) {
				$related_post = get_post( $related_post );
			}
			?>
		    <li>
		    	<a href="<?php echo esc_url( get_permalink( $related_post->ID ) ); ?>"><?php echo esc_html( get_the_title( $related_post->ID ) ); ?></a>
		    </li>
		<?php } ?>
		</ul>
	<?php
	}
	return ob_get_clean();
}

This is perfect! I expanded your concept here: https://gist.github.com/contemplate/167464f3a0de4a8dfad00a8e925d10bd