I noticed that some elements like text-box have required property.
But I have not found any documentation about form (or input) validation.
Maybe you have not implemented it yet and it is on the roadmap?
Or I am missing something and could not find it on your examples or API doc pages?
Set the required property by using the HTML Element's instance.
const textBox = document.querySelector('smart-text-box');
textBox.required = false;