I have a server action that I want opened in a new tab.

<record id="action_groupby_lead_analysis_wizard" model="ir.actions.server">
        <field name="name">Analyze Opportunities</field>
        <field name="model_id" ref="crm.model_crm_lead"/>
        <field name="binding_model_id" ref="crm.model_crm_lead"/>
        <field name="binding_type">action</field>
        <field name="state">code</field>
        <field name="code">
lead_ids = env.context.get('active_ids', [])
action = {
    'type': 'ir.actions.act_window',
    'res_model': 'groupby.lead.analysis.wizard',
    'view_mode': 'form',
    'target': 'new',
    'context': {'default_lead_ids': lead_ids,}
}
        </field>
    </record>

groupby.lead.analysis.wizard is a transient model

(The action need not be a server action. It just should be able to take selected lead_ids from the list view.)

Odoo v18 Community Edition