Hi,

You are not getting the required result on applying the domain is that you have selected the wrong record.Add the domain in the record with id product_template_action.

<record id="product_template_action" model="ir.actions.act_window">
    <field name="name">Products</field>
    <field name="type">ir.actions.act_window</field>
    <field name="res_model">product.template</field>
    <field name="view_mode">kanban,tree,form</field>
    <field name="view_type">form</field>
    <field name="view_id" ref="product_template_kanban_view"/>
    <field name="domain">[('sale_ok','=',True)]</field>
    <field name="context">{"search_default_filter_to_sell":1}</field>
    <field name="help" type="html">
        <p class="oe_view_nocontent_create">
            Click to define a new product.
        </p><p>
            You must define a product for everything you sell, whether it's a physical product, a consumable or a service you offer to customers.
        </p><p>
            The product form contains information to simplify the sale process: price, notes in the quotation, accounting data, procurement methods, etc.
        </p>
    </field>
</record>

Thanks