Hi,

You have to inherit the digest model and have to necessary fields like a boolean to activate or to send this value in the digest email and then an computed field to compute value.

You can refer existing modules in Odoo, where the digest.digest model is inherited and added new values.

Sample from POS module:

class Digest(models.Model):
    _inherit = 'digest.digest'

    kpi_pos_total = fields.Boolean('POS Sales')
    kpi_pos_total_value = fields.Monetary(compute='_compute_kpi_pos_total_value')

    def _compute_kpi_pos_total_value(self):
        if not self.env.user.has_group('point_of_sale.group_pos_user'):
            raise AccessError(_("Do not have access, skip this data for user's digest email"))
        for record in self:
            start, end, company = record._get_kpi_compute_parameters()
            record.kpi_pos_total_value = sum(self.env['pos.order'].search([
                ('date_order', '>=', start),
                ('date_order', ', end),
                ('state', 'not in', ['draft', 'cancel', 'invoiced']),
                ('company_id', '=', company.id)
            ]).mapped('amount_total'))

    def _compute_kpis_actions(self, company, user):
        res = super(Digest, self)._compute_kpis_actions(company, user)
        res['kpi_pos_total'] = 'point_of_sale.action_pos_sale_graph&menu_id=%s' % self.env.ref('point_of_sale.menu_point_root').id
        return res

Thanks & Regards

Walnut Software Solutions