Gotify is a self hosted push notification service.

We can use the generic REST provider.

Add a new notify service in /config/configuration.yaml

notify:
  - name: gotify
    platform: rest
    resource: https://gotify.yourdomain.tld/message
    method: POST
    headers: 
      X-Gotify-Key: your-gotify-api-key
    title_param_name: title
    message_param_name: message
    target_param_name: priority

This notification provider can be used in an automation like this, notice how the priority can be set with the target attribute: