I have created a Webhook-only App for my custom integration and it seems to working fine for me.
I am looking at your documentation https://developers.zoom.us/docs/api/rest/reference/zoom-api/events/#tag/webinar . I need to find a way to identify whether the participant joined Live or on-Demand (Attendance Type). In the Registration report which can be downloaded from zoom, it has a column name “Attendance Type” which will identify Live Vs on-demand. Do you have a similar flag to identify that in the webhook response?