ACF Gallery field - Custom Shortcode

shortcode.php

add_shortcode( 'custom_acf_gallery', function( $atts ) {
	$gallery_data = get_field( 'gallery' ); // change the field name accordingly.
	
	ob_start();
	
	if ( ! empty( $gallery_data ) ) {
	?>
	<div class="pp-post-gallery">
	<?php
		foreach ( $gallery_data as $image_data ) {
			$name = $image_data['filename'];
			$title = empty( $image_data['title'] ) ? $name : $image_data['title'];
			$alt = empty( $image_data['alt'] ) ? $title : $image_data['alt'];
			$sizes = $image_data['sizes'];
			$thumbnail = $sizes['thumbnail'];
			$url = ! isset( $sizes['medium'] ) || empty( $sizes['medium'] ) ? $thumbnail : $sizes['medium'];
			?>
			<div class="pp-post-gallery-item">
				<img src="<?php echo $url; ?>" alt="<?php echo esc_attr( $alt ); ?>" />
			</div>
			<?php
		}
	?>
	</div>
	<?php
	}
	
	return ob_get_clean();
} );

style.css

.pp-post-gallery {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
}