As paperless as possible when delivering sales - how do you handle it

Client would like to be as paperless as possible when delivering orders.

They would like to package up the order and invoice it (electronic delivery).   No problem here.

Driver takes it to their customer,  captures signature to link back to the invoice to confirm delivery (maybe merge it in and somehow reprint the invoice with the signature?) .   Ideally no paper invoice to the customer (although it seems to me that the customer would probably like to have at least a packing slip for verification and their own receiving work - so I'm not sure I can see eliminating at least a packing slip).

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How are you handling this type of thing?