Currently, this is not possible, because WhatsApp-Business has some limitation relation to “direct” contact of a person. To make this really working in a good way and to avoid unexpected behaviours (e.g. the 24-h customer window is already closed and the trigger can not sent seomthing), we would need to add WhatsApp-Business-Tempalte support (but this means also that the usage is difference from “cost” perspective on WhatsApp-Business side).
Suddenly the trigger has something like, only process the trigger when the 24-hour window is open, right? Otherwise, just send a public note.