Hi, I'd like to show intrastat_id field that is on product form in account move (when creating invoices)

I'm inheriting it like this

class ProductTemplate(models.Model):
_inherit = 'account.move.line'
 
product_template_id = fields.Many2one('product.template')
intra_stat = fields.Many2one(related="product_template_id.intrastat_id", string='Intrastat #')

It shows nothing - blank field in lines. What am I doing wrong? I double checked if Intrastat is set on product.