Woocommerce Bulk Resave/Update All Products

wbrsp.php

// This code will resave / update 200 woocommerce products every time you visit one of your pages. Increase or decrease limit depending on your server resources.
add_action( 'woocommerce_loaded', 'update_products_by_x' );
function update_products_by_x(){
    $limit = 200;

    // getting all products
    $products_ids = get_posts( array(
        'post_type'        => 'product', // or ['product','product_variation'],
        'numberposts'      => $limit,
        'post_status'      => 'publish',
        'fields'           => 'ids',
        'meta_query'       => array( array(
            'key'     => '_sync_updated',
            'compare' => 'NOT EXISTS',
        ) )
    ) );

    // Loop through product Ids
    foreach ( $products_ids as $product_id ) {

        // Get the WC_Product object
        $product = wc_get_product($product_id);

        // Mark product as updated
        $product->update_meta_data( '_sync_updated', true );

        $product->save();
    }
}

Original code by LoicTheAztec: https://stackoverflow.com/a/55966698/11055908