You are required to add a single line of code if you wish to add validator on any other page which isn't a homepage.
Demo link: https://rbz-section.myshopify.com/products/peasant-top-in-pale-pink
In following example, we will add zip code validator on Product page. You can add this on pages like cart, CMS, product or a collections page.
1. Go to App > Global Settings.
2. Change restriction type to be "Section (widget)"
3. Visit your stores admin panel.
4. Click on "Online Store" > "Themes" > "Actions" > "Edit code"
5. Open "product-template.liquid" file which you can find under "Sections". Add following code snippet at appropriate location.
Location can change depending on theme you are using. Please contact your theme developer if you are unsure about where to place.
In this example, we are adding validator above product details (name, price, buy button).
6. Save page and you should see validator on your product details page.