partner-contact/base_location_nuts/views/res_partner_view.xml

<?xml version="1.0" encoding="utf-8" ?>
<odoo>
    <record model="ir.ui.view" id="view_partner_form_nuts">
        <field name="name">Partner form with NUTS</field>
        <field name="model">res.partner</field>
        <field name="inherit_id" ref="base.view_partner_form" />
        <field name="arch" type="xml">
            <xpath expr="//sheet/group//field[@name='country_id']/.." position="after">
                <field name="nuts1_id" />
                <field name="nuts2_id" />
                <field name="nuts3_id" />
                <field name="nuts4_id" />
            </xpath>
            <xpath
                expr="//field[@name='child_ids']/form//field[@name='country_id']/.."
                position="after"
            >
                <field name="nuts1_id" />
                <field name="nuts2_id" />
                <field name="nuts3_id" />
                <field name="nuts4_id" />
            </xpath>
        </field>
    </record>
    <record model="ir.ui.view" id="view_res_partner_filter_nuts">
        <field name="name">Partner search with NUTS</field>
        <field name="model">res.partner</field>
        <field name="inherit_id" ref="base.view_res_partner_filter" />
        <field name="arch" type="xml">
            <field name="category_id" position="after">
                <field name="nuts1_id" />
                <field name="nuts2_id" />
                <field name="nuts3_id" />
                <field name="nuts4_id" />
            </field>
            <filter name="salesperson" position="after">
                <filter
                    name="nuts_l1"
                    string="NUTS L1"
                    domain="[]"
                    context="{'group_by': 'nuts1_id'}"
                />
                <filter
                    name="nuts_l2"
                    string="NUTS L2"
                    domain="[]"
                    context="{'group_by': 'nuts2_id'}"
                />
                <filter
                    name="nuts_l3"
                    string="NUTS L3"
                    domain="[]"
                    context="{'group_by': 'nuts3_id'}"
                />
                <filter
                    name="nuts_l4"
                    string="NUTS L4"
                    domain="[]"
                    context="{'group_by': 'nuts4_id'}"
                />
            </filter>
        </field>
    </record>
</odoo>