Email the invoice when the sale shipment is authorised ( Automation)

Organization: The Pure Food Co

The customer has requested the ability to automatically email the invoice when the sale shipment is authorised, using the "Run this workflow when sale shipment is authorised" trigger within Automations.
 
They are aware that this functionality is available under the "Sale invoice is authorised" workflow trigger. However, their requirement is to trigger the invoice email when the shipment is authorised instead.
 
I informed the customer that this is not currently supported under the shipment-authorised workflow criteria. As a result, they have requested for this to be submitted as a feature request.