Merchant submitted code snippet to display only the next statuses configured with Order Status Manager for certain user roles

only_display_next_status.php

<?php // Only copy if required!

/**
 * Custom code to display only the "next status" status for `orders_manager` role in the WooCommerce
 * edit order screen - status selection, in order to keep to a specific order workflow.
 */
function hide_specific_order_statuses_for_user_role() {

	global $post;

	// check if user has user role "orders_manager"
	if ( ! current_user_can( 'orders_manager' ) ) {
		return;
	}

	// check if we are on a post
	if ( strpos( $_SERVER['REQUEST_URI'], 'post.php?post=' ) === false ) {
		return;
	}

	// check if the post we are on is with post type "shop_order"
	if ( empty( $post ) || 'shop_order' !== $post->post_type ) {
		return;
	}
	?>
	<script>
		jQuery(function () {
			<?php

			global $woocommerce, $post;

			// current order
			$order = new WC_Order( $post->ID );

			// slug of the current order status of the order
			$status = new WC_Order_Status_Manager_Order_Status( $order->get_status() );

			// "Next statuses" of the current order status
			$next_statuses   = $status->get_next_statuses();
			$total_statuses  = count( $next_statuses );
			$option_selector = '';

			// for each "Next statuses"...
			for ( $i = 0; $i < $total_statuses; ++$i ) {
				// ...get the current "Next statuses"-status in the loop...
				$current_next_statuses = new WC_Order_Status_Manager_Order_Status( $next_statuses[$i] );
				// ...and make a part of a jQuery selector string that target elements that does not have that current "Next statuses"-status as a value
				$option_selector .= '[value!="wc-' . $current_next_statuses->get_slug() . '"]';
			}
			// make a jQuery selector string that target the "Status:" select field (#order_status), and inside that target all the options that does not have a value from the "Next statuses"-loop above. remove those options. Notice that the current order status is not removed becouse it is excluded from the jQuery selector with the "not()".
			echo 'jQuery(\'#order_status option' . $option_selector . '\').not(\'#order_status option[value="wc-' . $order->get_status() . '"]\').remove();';
			?>
		});
	</script>
	<?php
}
add_action( 'admin_head', 'hide_specific_order_statuses_for_user_role' );
?>

Thanks Daniel!