I have the same problem for an NGO I am working on a project with to use a few of the OSDonation modules. I have an idea for a solution that is outside of the modules to some degree and hope that they can read this to confirm my thoughts .
1. sign up for a WhatsApp service company such as Ultramsg
2. Use their backend integration api that can be used with Joomla.
3. This is the question for OSDONATION is that you world need a completion workflow after the Event or other module produces the PDF files to then using the Api to send the document to the WhatsApp phone number of the user that has made the booking for the event.
p.s Ultramsg plans are reasonable at $39 for unlimited use per month .
in regard to point three I have posted a request to ascertain if the following would work in that you would use the UltraMsg PHP curl code in this section documented
would it work under the following section
This event is triggered when status of the registration record changed from Pending to Paid (after payment is completed or admin change status of registration record from Pending to Paid in case registrant using offline payment method for the registration)public function
It does seem that this is a logical place where it should work
Last edit: 4 months 2 days ago by Mr Leslie Jarrett. Reason: more info