If app is not working for soldout products or variants?

There are 2 reasons :

1. If full product form is inside the product.available condition

{% if product. available %}
    

{% endif %}

You just need to remove the condition.

2. Soldout variants may be disabled in theme.

Find following code in product form. ( tag with name="id" property)

    {% for variant in product.variants %}
    {% if variant.available %}
        
            {{ variant.title }} - {{ variant.price | money_with_currency }}
        
            {% else %}
        
            {{ variant.title }} - {{ 'products.product.sold_out' | t }}
        
    {% endif %}
    {% endfor %}

Find following code

replace with