Tried https://www.odoo.com/nl_NL/forum/help-1/how-to-search-for-vendor-product-code-in-product-list-264308

But that doesn't seem to work: https://snipboard.io/7mYHdM.jpg

If I look for products it won't look for the vender product code.

https://snipboard.io/pQrJ9S.jpg

So I'm looking on the wrong place?

I was looking for the wrong function, this seems to work:

<xpath expr="//field[@name='name']" position="attributes">
    <attribute name="filter_domain">
        ['|', '|', '|', '|',
        ('default_code', 'ilike', self), 
        ('product_variant_ids.default_code', 'ilike', self),
        ('name', 'ilike', self), 
        ('barcode', 'ilike', self),
        ('seller_ids.product_code', 'ilike', self)
        ]
    </attribute>
</xpath>

Did you search the Forum to check if this was already answered?

https://www.odoo.com/forum/help-1/how-can-i-search-my-products-by-the-code-and-or-name-that-the-supplier-vendor-has-for-them-245435

https://www.odoo.com/forum/help-1/how-to-search-for-vendor-product-code-in-product-list-264308