Hi,

Odoo does not include out-of-the-box functionality for restricting products to specific customers. The standard product setup only allows assigning suppliers to products not customers.So,

you need to develop a custom module that adds the overrides for this.

Try the following method.

1- Add a Many2many field on sale.order to hold allowed products.

2-Compute or update that field when partner_id is selected

3-Add a domain on product_id in sale.order.line based on order_id.allowed_products

Explanation.

1. Extend sale.order to Add Allowed Products Field.

       from odoo import models, fields, api

class SaleOrder(models.Model):

    _inherit = 'sale.order'

    allowed_products = fields.Many2many(

        'product.product',

        string='Allowed Products',

        compute='_compute_allowed_products',

        store=False,

    )

    @api.depends('partner_id')

    def _compute_allowed_products(self):

        for order in self:

            if order.partner_id:

                # Fetch products for that customer

                # You must define a customer-product link. Here's an example:

                customer_products = self.env['product.product'].search([

                    ('allowed_customer_ids', 'in', order.partner_id.id)

                ])

                order.allowed_products = customer_products

            else:

                order.allowed_products = self.env['product.product']

2. Add a New Field on Product to Link Allowed Customers

   class ProductProduct(models.Model):

    _inherit = 'product.product'

    allowed_customer_ids = fields.Many2many(

        'res.partner',

        string='Allowed Customers'

    )

You can use this to assign products to specific customers

3. Extend sale.order.line  view with Domain on product_id

<field name="product_id" domain="[('id', 'in', order_id.allowed_products)]"/>

* This method is clean, modular, and respects Odoo’s domain mechanism.

* You can also restrict product search in product.template view if needed.

* Remember: this limits product selection but doesn’t prevent manual changes in backend unless you add constraints.

Hope it helps