I’m not sure if this meets your requirements, but here’s what it looks like to me.
notify:
- name: ntfy
platform: rest
method: POST_JSON
data:
topic: secret-topic
title_param_name: title
message_param_name: message
resource: https://ntfy.sh
In the node-red addon I configured node-red-contrib-sse-client for incoming ntfy messages. But the ‘websocket in’ node works for that too.