Require an Image, SKU and Price Before Publishing Products

$wpide_publish_requires = array( 'image', 'sku', 'price' ); // Checks to run.

add_action( 'woocommerce_admin_process_product_object', function ( $product ) use ( $wpide_publish_requires ) {
    if ( 'publish' !== $product->get_status() ) {
        return;
    }

    $missing = array();

    // phpcs:disable WordPress.Security.NonceVerification -- WooCommerce verifies the product save nonce.
    if ( in_array( 'image', $wpide_publish_requires, true ) && ! $product->get_image_id() && empty( $_POST['_thumbnail_id'] ) ) {
        $missing[] = 'a featured image';
    }
    // phpcs:enable

    if ( in_array( 'sku', $wpide_publish_requires, true ) && '' === (string) $product->get_sku() ) {
        $missing[] = 'a SKU';
    }

    if ( in_array( 'price', $wpide_publish_requires, true ) && ! $product->is_type( array( 'variable', 'grouped', 'external' ) ) && '' === (string) $product->get_regular_price() ) {
        $missing[] = 'a regular price';
    }

    if ( in_array( 'price', $wpide_publish_requires, true ) && $product->is_type( 'variable' ) && ! $product->get_variation_price( 'max' ) ) {
        $missing[] = 'a priced variation';
    }

    if ( $missing ) {
        $product->set_status( 'draft' );
        set_transient( 'wpide_publish_blocked_' . get_current_user_id(), $missing, 60 );
    }
}, 99 );

add_action( 'admin_notices', function () {
    $missing = get_transient( 'wpide_publish_blocked_' . get_current_user_id() );

    if ( $missing ) {
        delete_transient( 'wpide_publish_blocked_' . get_current_user_id() );
        printf( '<div class="notice notice-error"><p>%s</p></div>', esc_html( 'The product was saved as a draft because it is missing ' . implode( ', ', $missing ) . '. Add them and publish again.' ) );
    }
} );