Ah, I hoped your Whatsapp pack already had actions to work with the graph.facebook.com.
I just managed to authenticate and start receiving Whatsapp webhooks directly into Coda with my upcoming Doc as API pack/service.
I mean, this is my “server”, no need for any Brazilian API (although I’m gonna charge for my service as well):
Now I only need to properly respond to these (e.g. send some reply messages)