Try this out.
Please note that all your requirement is not related to Shortcoder and I’ve been providing these custom code just to help you and to get you some idea to write your own. For any more custom requirements, I may not be available.
Please do try the code below and I tested it works.
function modified_date_shortcode( $atts ) {
$atts = shortcode_atts( array(
'post_id' => ''
), $atts);
global $post;
$post_id = empty($atts['post_id']) ? $post->ID : $atts['post_id'];
$date = get_the_modified_date( 'F j, Y', $post_id );
$date_full = get_the_modified_date( 'c', $post_id );
return '<time datetime="' . $date_full . '"><i class="far fa-calendar"></i> ' . $date . '</time>';
}
add_shortcode( 'modified_date_sc', 'modified_date_shortcode' );
Shortcode: [modified_date_sc]
or [modified_date_sc post_id="1234"]
Thanks,
Aakash