Hello,

I have added many2many field in kanban view of Leads (crm.lead). The same way we can add many2one field.

Try this. 

<xpath expr="/kanban/templates/t[@t-name='kanban-box']/div/div[@class='oe_kanban_content']/div[@style='padding-left: 0.5em']" position="after">

    <div>

        <field name="categ_ids"/>

    </div>

 </xpath>

Hope this will help you.

Thanks,