Automatically link to WooCommerce Product Variation detail when searching for a Product Variation SKU

functions.php

<?php

// When using SearchWP it's necessary to disable WooCommerce's insistance on
// automatically redirecting to a single search result without showing the
// search results page, when that happens this hook doesn't run!
// Willing to bet this can be edited to accommodate, tips are welcome!
add_filter( 'woocommerce_redirect_single_search_result', '__return_false' );

function my_maybe_woocommerce_variation_permalink( $permalink ) {
	if ( ! is_search() ) {
		return $permalink;
	}

	// check to see if the search was for a product variation SKU
	$sku = get_search_query();
	$args = array(
		'post_type'       => 'product_variation',
		'posts_per_page'  => 1,
		'fields'          => 'ids',
		'meta_query'      => array(
			array(
				'key'     => '_sku',
				'value'   => $sku,
			),
		),
	);
	$variation = get_posts( $args );

	// make sure the permalink we're filtering is for the parent product
	if ( get_permalink( wp_get_post_parent_id( $variation[0] ) ) !== $permalink ) {
		return $permalink;
	}

	if ( ! empty( $variation ) && function_exists( 'wc_get_attribute_taxonomy_names' ) ) {

		// this is a variation SKU, we need to prepopulate the filters
		$variation_id = absint( $variation[0] );
		$variation_obj = new WC_Product_Variation( $variation_id );
		$attributes = $variation_obj->get_variation_attributes();

		if ( empty( $attributes ) ) {
			return $permalink;
		}

		$permalink = add_query_arg( $attributes, $permalink );
	}

	return $permalink;
}

add_filter( 'the_permalink', 'my_maybe_woocommerce_variation_permalink' );