I dig into this when you post it and that menuitem is an action client meaning that there is a widget like view for that specific view. If you wanna reuse it in another menu you need to declare something like this from the original Odoo code:

<record id="mail_inboxfeeds" model="ir.ui.menu">
    <field name="name">Inbox</field>
    <field name="sequence" eval="10"/>
    <field name="action" ref="mail.action_mail_inbox_feeds"/>
    <field name="parent_id" ref="mail.mail_feeds"/>
</record>