KubeJS REI Runtime lets you show/hide items in REI dynamically, it provides these methods by default:
// in client_scripts
REIRuntime.showItem(item); // shows an item in REI
REIRuntime.showItems([item, item, ...]); // shows items in REI
REIRuntime.hideItem(item); // hides an item in REI
REIRuntime.hideItems([item, item, ...]); // hides items in REI
